I don't know what you consider mind-blowing, but I find this pretty disturbing:
According to The Lancet (British medical journal), "1 million children are forced into prostitution every year and the total number of prostituted children could be as high as 10 million." This was, according to them, a conservative estimate.
Another interesting fact I learned recently is that China has one of the highest amount of consensual prostitutes, many don't even have pimps. That isn't to say they enjoy being prostitutes, but rather that they've decided to resort to prostitution instead of being forced. I think many people would find this surprising.