The trouble with sex trafficking stats is that a lot of them are misrepresented or even have no basis in fact whatsoever - even ones from supposedly-reputable sources like the United Nations and the Department of Justice - and it's very difficult to figure this out since they're usually not properly cited.

For example, that 9.5 billion figure isn't anywhere in the UN page it's cited to. So far I've traced it as far as a DoJ report from 2004 which claims: "According to the UN, human trafficking is the third largest criminal enterprise worldwide, generating an estimated 9.5 billion USD in annual revenue according to the U.S. intelligence community." No specific citation for that claim, naturally, but it looks like originally it was just a guess that some unnamed intelligence community pulled out of their ass.