Think i was wrong in my earlier asumption that there isn't any statistics on this.
I came across this:
http://www.cdc.gov/nchs/data/hus/hus08.pdf#066
I may have misread some statistics here so correct me if im wrong.
This document claims that about 20% of everyone beetween 18-25 years in the US has tried an illegal drug, 16% of these having done marijuana.
And as you can see the use is down to 11% with people 26-34 years of age.
After that its 5% for people 35 years and above.
I dont think you have that many addicts in your country.