http://www.casacolumbia.org/download/file/fid/640, question 44:
Which is easiest for someone your age to buy: cigarettes, beer or marijuana?
31% CIGARETTES
14% BEER
34% MARIJUANA
5% THE SAME
15% DON'T KNOW/NO RESPONSE
Then this poll like so many is useless because I have teens and asked them plus asked their friends earlier today after your posts and my wife works with teens.
But hey if you want to believe a poll what suits your theory then go right ahead and I will go with first hand knowledge