I already know, but before I put the graphs up sometime soon, let's hear from the peanut gallery. Try to say just 1 year, though a range of 3 years is OK too. Anything more than that and it's pretty easy to guess right. "Sluttiness" here means burning through lots of guys in a given time.
For any age between 15 and 55, there's a megaphone-grabber in popular culture that is certain that such women are on a cock-gobbling rampage, so that won't help. Time to put on your thinking caps.