In the U.S. I would say it's a huge problem.
For high school kids do you know what the easiest thing to get is?
Marijuana. Even for the kids that don't do drugs, if they wanted to get high, it's only a few phone calls away.
I have noticed this especially in California. I think out of all the high school kids I know, 1 out of 5 are straight. The rest do some sort of drug.