Was looking at the issue of access (marijuana v. alcohol). There is some support for those who say marijuana is easier (or just as easy) to get as alcohol:
An Issue of Accessibility
Both alcohol and marijuana are dangerous for adolescents, but which is easier for teens to get? Despite the fact that alcohol is a legal drug, often stored in parents' liquor cabinets and available for purchase if teens know someone over 21 years old, experts and adolescents say that marijuana is now easier for teens to get their hands on than alcohol.
http://www.adolescent-substance-abuse.com/substance-abuse/is-marijuana-or-alcohol-having-more-impact-on-your-teen.htmOn the other hand, alcohol use by teens apparently dwarfs marijuana use:
How Many Teens Use Marijuana?
Some people mistakenly believe that “everybody's doing it” and use that as an excuse to start using marijuana themselves. Well, they need to check the facts, because that’s just not true. According to a 2009 survey called Monitoring the Future, about 7 percent of 8th-graders, 16 percent of 10th-graders, and 21 percent of 12th-graders had used marijuana in the month before the survey. In fact, marijuana use declined from the late 1990s through 2007, with a decrease in past-year use of more than 20 percent in all three grades combined from 2000 to 2007. Unfortunately, this trend appears to be slowing, and marijuana use remains at unacceptably high levels, as the most commonly used illegal drug.
http://teens.drugabuse.gov/facts/facts_mj1.phpCompared with:
Just about everyone knows that the legal drinking age throughout the United States is 21. But according to the National Center on Addiction and Substance Abuse, almost 80% of high school students have tried alcohol.
http://kidshealth.org/teen/drug_alcohol/alcohol/alcohol.htmlAnd this:
Alcohol access by minors
A survey of over 6000 teenagers revealed (1):
* Teenagers usually get their alcohol from persons 21 or older. The second most common source for high school students is someone else under age 21, and the second most common source for 18- to 20-year-olds is buying it from a store, bar or restaurant (despite the fact that such sales are against the law).
* In the 12th grade, boys were more likely than girls to buy alcohol from a store, bar or restaurant.
* The higher a teenager's weekly income, the more likely he/she will buy alcohol from a store, bar or restaurant.
* It is easy to get alcohol at a party and from siblings or others 21 or older.[12]
How easy is it for youth to buy alcohol?
Young females attempted to buy beer without an ID at liquor, grocery or convenience stores:
* In 47–52% of the attempts, beer was sold. (1, 2)
* Nearly 80% of all the stores sold beer to the buyers at least once in three attempts; nearly 25% sold beer all three times.(1)
When young females attempted to buy beer without an ID at bars or restaurants, 50% of the attempts resulted in a sale to the buyer.(2)
When young males and females attempted to buy beer without an ID at community festivals, 50% of the attempts resulted in a sale to the buyer.(3)[12]
http://en.wikipedia.org/wiki/Alcohol_consumption_by_youth_in_the_United_States