Where the hell am I gonna find numbers on that. Just look at your local area though. Go to liquor establishments. Bars, stores, ect. Count how many under 21 buy compared to 21. Then go count how many underage buy at the "back alley" spots. Many times more alcohol is purchased by 21+ Do to some simple facts. They don't have to worry about getting arrested. They have easier access and they know what they are buying.
And of course Meth is more addictive than Alcohol. I'm not even waisting my time to pull the numbers to prove that universally known fact.
You shouldn't make a "guarantee" if you're not ready to back it up with hard numbers.