It floats around 5-8% average (with a few studies a little higher) depending on the year in the last decade, that's up from 2-4% in the 90's - very early 2000's. That being said, a lot of this is self reported, so who knows. There are probably some using for medical reasons, some that mistake corticosteroids for A/AS, and the goofs that think anything from GNC is a steroid. On the flipside of that, there are probably smart kids that keep their mouth shut. I'm not surprised that it rose a bit, given that steroid info is much more available, and you had the pro-hormone boom for many years.
Another interesting thing is a look at actual teenage athletic steroid busts the last few years - NJ was conducting about 500 tests a year, they never had a rate higher than 1% positive. Illinois tested around 700, had no positives. Texas conducted 10000 tests in 2007, it had 6 positives, 2011 it tested 3300, and had 9.
Noted steroid researcher Charles Yesalis used to put his estimate at 600,000 - 1,000,000 HS aged users depending on the year you spoke to him, When you consider the number of High school students is probably around 12-15 million the last couple of decades, it's in line with other sources.
