I believe the overall percentage of kids who need these drugs is extemely small. And lots of "doctors" are perscribing them because they are useful idiots.
My daughter a few years back had a school administrator say she should be checked for ADD and ADHD because she'd forget to turn assginments in and other similar stuff.
We took her to the MD she'd seen since birth (she was 12 or so at the time) and ol' Doc Silverstein looked in her eyes and ears, asked her a couple of questions and proclaimed tha she indeed "has a touch of ADD."
I said you're out of you mind and we've never been back to that crackpot since. Oh, and my daughter is doing just fine in school and otherwise.