A lot has been said about how many prostitutes are forced. Numbers keep flying around that range from anywhere between 8% to 90%. So I decided to give a good and final overview of the researches my and my boyfriend could find with actual numbers about this. We spend a lot of time on going through them and trying to figure out where the numbers come from exactly, what they're based upon and who they are based on. I have put the researchers in descending order, meaning we start with the highest number and work our way down to the lowest number with a conclusion at the end to wrap things up. I would like to state that these numbers are not my personal opinions, but simply the numbers as they can be found in the rapports with the page numbers to help you find them. The titles of the rapports will lead you directly to the rapport itself, so it should be easy to verify my findings.

KLPD Schone Schijn (2008)
This rapport is also known as the Sneep-research, but later got a new cover on it and was re-named to Schone Schijn. This rapport speaks of 50 to 90% forced and/or exploited prostitution. It is often being mentioned in the media, mostly by politicians. Also Gert-Jan Segers and Myrthe Hilkens used these numbers when they defended their quest to do research about the Swedish model on the Dutch TV talkshow of Pauw & Witteman. Furthermore Jojanneke van den Berge her claim of 70% forced prostitution is based on an interview with Werner ten Kate, who based this upon this research together with the Koolvis case, as you can read here.

What is the 50-90% based upon?
The 50 to 90% is based upon the estimations of only 6 people from the police (page 76). It is not based upon any research or interviews with the target group itself, the prostitutes, but on near guesswork. Interesting detail is here that 18 police officers were questioned (page 134), but only 6 answered the question (page 76). The other 12 police officers stated that it was impossible to give any estimations.

Is it reliable?
The police and other government authorities themselves always claim that they have little insight in the problems of human trafficking and forced prostitution. So keeping that in mind with the fact that this number is based on estimations of only 6 people from the police themselves I'd have to say: NO.

Bureau Beke Kwetsbaar Beroep
This rapport is often mentioned as a rapport that would say that 30-40% of the prostitutes are forced. The rapport however doesn't get mentioned very often, as other more extreme statistics exist for interest groups of both sides to claim.

What is the 30-40% based upon?
The 30-40% get's only mentioned in the rapport (page 164), but is never actually used by the rapport itself as a conclusion. In the rapport it literally states:

"Sommigen, onder andere uit de hoek van politie, noemen de eerder genoemde schatting van 90 procent uit het Sneep-onderzoek ‘overdreven’ en vinden 30-40 procent realistischer."

Translation:
"Some others among which people from the police, called the earlier made estimation of 90 percent from the Sneep-research 'exaggerated' and think 30-40 percent is more realistic."

Is it reliable?
Given the fact that it is (again) only mentioned by other people as a number, we would have to conclude that it's not very reliable. Also the fact that the rapport only interviewed 8 prostitutes (page 223), gives away that the researchers did not spend a lot time talking with the target group itself. Besides that it does put more question marks surrounding the reliability of the Schone Schijn rapport. So I'd have to say: NO.

ASO De Amsterdamse Prostitutie Monitor (2010)
This rapport speaks of 10% forced prostitution. It hardly ever gets mentioned in the media, despite the fact that the research is done among 94 women from the Red Light District in Amsterdam itself.

What is the 10% based upon?
The 10% is based upon the answers of 94 prostitutes who were interviewed anonymously (page 29). The research was done in the Amsterdam Red Light District areas, making it only useful when we speak about window prostitution in Amsterdam, and not representative for prostitution as a whole or other forms of prostitution.

Is it reliable?
One could question the honesty of the answers, because often people claim that prostitutes themselves would be scared to admit it because of their pimp. However, the research was done anonymously, which would take away any doubts about not answering it truthfully. After all, nobody will find out it was you who answered it, thus you would be safe from your pimp.
Also the fact that 9 girls admitted being forced during the anonymous interviews, shows that apparently the women are not scared to say it, which goes in against the assumption that they would be scared.

Scharlaken Koord
This rapport is not available anymore online, but we know of it's existence, since it gets mentioned in many other rapports as well (Kwetsbaar Beroep for instance). We know that the conclusion of the rapport was 8% forced prostitution.

What is the 8% based upon?
We know from other rapports that mentioned the research from Scharlaken Koord, that 220 prostitutes from the Red Light District were interviewed. Unfortunately the source is not available online anymore, but given the fact that this many prostitutes were interviewed for the rapport, it is likely they are based upon the answers of the prostitutes themselves.

Is it reliable?
Given the fact that the research was done by a christian organisation focused on helping prostitutes who became in victims, which is located in the Red Light District itself, and given the fact that christian organisations usually give very high estimates due to their moral issues surrounding prostitution, it sounds likely these numbers could be correct. Also given the fact that the answers (probably) came from 220 prostitutes themselves, would defend the notion that these could be accurate.
Another interesting detail is that Scharlaken Koord themselves often claim that 80% are forced, even though their own research states otherwise, but perhaps this could explain the absence of the source itself online. After all, they are an organisation depending on donations, and they therefore have a financial interest in claiming high statistics for their own benefit, something we often see from rescue organisations.

Regioplan Evaluatie Opheffing Bordeelverbod (2006)
This rapport was done for the WODC for the Ministery of Justice in Holland. It usually only gets mentioned in numbers, when people say: "The numbers range from anywhere between 8 to 90%, so we don't know." This rapport shows that only 8% would be forced.

What is the 8% based upon?
The 8% is based upon the interviews done with 354 prostitutes (page 6) throughout the entire country and in various different types of prostitution, from window prostitutes to prostitutes working in brothels and so on (page 7). Also 11 male prostitutes were interviewed (page 7), which is a group that is often forgotten, but not less alive even though they only are about 3% of the total interviewed prostitutes.

Is it reliable?
This is the largest group of prostitutes ever interviewed in Holland about their own profession for a research about this. Beyond that, the statistics come from their own answers. Of course one might question the reliability of their answers, but than again, so can one question the reliability of the answers a prostitute gives to a police man. Also, the fact that 32 of the interviewed prostitutes stated that they are being forced, shows that apparently they are not scared to admit it, which again goes in against the assumption that they would be afraid to do so.

The Nationaal Rapporteur (2013)
The Nationaal Rapporteur is the person who anually gives out a rapport about human trafficking. In her latest numbers the Rapporteur comes to 1437 'possible'victims. It does not speak of percentages, but based upon the estimated 20.000 prostitutes in Holland this would come down to about 7,18%.

What is the 1437 'possible' victims based upon?
The 1437 are based upon numbers from CoMensha (page 4), which is the organisation that collects all the data of possible victims that are registered by the government and NGO's. The numbers come for example from the Royal Netherlands Marechaussee (KMar), who have a registration obligation for each 'possible' victim they come across (page 26). This means that every person the KMar thinks could be a victim, has to be registered, regardless of the fact if she really turns out to be a victim or not. A few examples of this can be found in the full rapport here, in where they write (page 78):

"In the course of the controls of the so-called “risk flights” out of Bulgaria, the ‘sluisteam’ (part of the border control) of the KMar [Koninklijke Marechaussee: Royal Dutch Marechaussee, or Marshals] spoke with a Bulgarian woman. This woman has been checked multiple times by the KMar when she arrived in the Netherlands, and she indicated that this was tedious. She claims to (“still”) not have anything to do with prostitution. This time she says that she is coming to the Netherlands for 3 days to visit a number of friends.  From further observation by the KMar officers to identify a possible person picking her up it seems that the woman went to the information desk of the Dutch Railway (Nederlandse Spoorwegen or NS), then made contact with someone via a public telephone, and made contact with someone again with her mobile phone. She subsequently left the airport by train. The KMar registered the woman with CoMensha."

And another example here (page79-80):
"In the course of the controls of the so-called “risk flights” out of Bulgaria, the ‘sluisteam’ (part of the border control) of the KMar at Schiphol spoke with a highly educated Bulgarian woman. The woman admitted during a conversation with the KMar officers that she has lived in Amsterdam since sometime in 2010 and since about then has worked as a prostitute in the Netherlands, for which she registered herself with the Chamber of Commerce. She couldn’t give her monthly earnings from prostitution, but she does report that the earnings are not much and that she has kept a written record of the precise details. She can give her expenses, which concern 1,250 euros for the rent of her house, 90 euros for the rent of a window during the day and 100 euros for the rent of a window at night. After the conversation with the woman, the KMar officers observed whether the woman would be picked up. However, this seemed not to be the case: the woman simply left the airport by taxi. She was reported for registration with CoMensha."
(Read more about this on Marijke Vonk her website)

Is it reliable?
The examples given above from the rapport itself show that the 'possible' victims that are registered by CoMensha are questionable. People that are just visiting friends in Holland are being reported as 'possible victims', without any clues as to why they got reported. Also a prostitute who gives no indication of being a victim, is being reported without an indication as to why she would be a 'possible victim'.
Another interesting fact is that the registration are done per case, and not per person. This means that the same person could appear several times as different registrations, and also get counted by the National Rapporteur as different people, even though it's the same person.
I've experienced in person being questioned exactly the same way by the KMar as depicted in the examples above, and therefore I am also 100% sure that I am registered several times in this rapport, and counted as multiple 'possible victims', even though I'm not a victim and I am just one person. Also other girls I know, many of them in fact, describe the exact same thing, meaning they are also being registered multiple times as different 'possible victims', even though they aren't.
It is therefore difficult to say how many of the 1437 'possible' victims are real victims, versus how many are registered because of false hunches or pure randomness. It does however show one thing, that in the eyes of the police and other authorities, many women are falsely being seen as 'possible' victims while in reality they are not, which would also explain the statistics of Schone Schijn.

Conclusion
There have been many numbers going around about how many prostitutes would be forced and/or exploited. Some people claim it's 70%, but there is no actual research to support that conclusion. Also the claim that it would be 50 to 90% does not seem very likely, since the research is based upon the opinions of some individuals, and not based upon any research among prostitutes themselves.

On the other hand there have been three researches which show a very similar image. Both Scharlaken Koord and Regioplan show the same percentage, and the ASO rapport comes to a conclusion which only differs 2% from the other two researches. Furthermore these three researches are also based upon actual research among the prostitutes themselves, and therefore don't state opinions but facts.

These numbers also seem consistent with the numbers from the Nationaal Rapporteur, who wrote in her latest rapport that in 2013 there were 1437 'possible' victims registered by CoMensha (page 4).
If we base ourselves upon the estimated 20.000 prostitutes in Holland, that about 1437 could be possible victims, that is 7,18% of the total amount of estimated prostitutes in Holland, very close to the estimations of the other three researches of Scharlaken Koord ASO and Regioplan, while very far away from the KLPD their rapport.

This would mean that 4 rapports all point in the same direction, that the number of forced prostitutes in Holland is somewhere around 7-10%. While on the other hand there is only one rapport that points toward an estimation of 50-90%, which is only based on opinions, and many other researches point out that these numbers are exaggerated and unlikely. Beyond that, the 4 rapports come from different sources, of which two are from the government themselves, which would furthermore support their reliability.

How many women are forced in Amsterdam's Red Light District?
It is almost impossible to say how many women are forced in Amsterdam's Red Light District, since we don't know how many women work there. The estimations vary between 700 and 1100 annually for the whole of Amsterdam. But the Amsterdam Red Light District is not the only place with window prostitution, since there are only about 296 windows in the Red Light District itself. Which means that only a portion of those 700-1100 women work in the Red Light District, and others work in other areas in Amsterdam where they have window prostitution, such as the Singel area and the Ruysdaelkade.

But even if all the windows in the Red Light District would be filled every day with women, there's only place for 592 women in total (296 during the day shift, 296 during the evening/night shift).
But whoever walks in the Red Light District during the day, will see that almost 75% of the windows are empty. So, if we calculate that during the day only 25% of the 296 windows are occupied, we would come down to 74 women working during the day, and 296 women during the evening, giving a total of 370 women working on one day.
Of course there are those that cannot always get a room, and will work behind the windows that are not occupied during another prostitute her free day. That group of girls that don't have their own fixed window, and stray from one window to another is however not larger than 100 girls I know from my own personal experience.

So let's say there are about 370 women with their own fixed window, and about 100 girls that stray from window to window each day. This will give us a total of maximum 470 women. Given that the highest reliable estimate of forced prostitution is 10%, this would come down to 47 women annually that are forced.
But of course those 47 women don't work all at the same time. So those will be over a time span of about one year, and we know from experience that women that are forced these days quickly get picked up by the police, as most forced prostitution cases show that these day they don't work there any longer than 6 months at the most.

During the night, based upon the fact that most windows will have a prostitute inside, and based upon the 296 windows that are available. We are talking about 30 women that could be forced to work there.
During the day however, there are roughly about 74 women working there, and based upon the estimated 10%, this would come down to about 8 women that could be forced.
In total this would come down to 38 women on a daily base, which is something very different from the 400 women that the mayor, Eberhard van der Laan, always claims in his speeches about prostitution in the Red Light District.

On a national level
The estimations about how many prostitutes work in Holland vary greatly from 15.000 to 35.000. It therefore seems also almost impossible to give any good estimations about how many prostitutes are really forced in Holland, since they would vary from 1200 to 3500, meaning the lowest number would be less than half of the highest estimations. Such large differences in estimations are unreliable in researches, which always use the rule that the margin can be no bigger than 5% for an accurate estimation.

Therefore we have to conclude that we simply don't know how many women are being forced into prostitution on a national level. There could be 3500, but they could also be 1200. In both cases however we are talking about a large number, and the problem should be fought.
But stating that 70% of the prostitutes would be forced, seems unlikely, and therefore also not very helpful in the fight against forced prostitution. After all, stating such statistics only makes it more difficult to identify the victims from the non-victims, since you would be searching for a much larger group than it in reality is. This makes it more obscure to find those victims, and doesn't help in the fight against forced prostitution.

It would be better to state that nobody knows, but that we should all keep our eyes open. That way people won't get a false image, but people still will keep their eyes open. It would help if people would report suspicions, rather than just report people randomly based upon the fact that they are from Romania for example, just because they are female and young, as the KMar does right now.

Dutch version