This isn’t new, or startling, but it was interesting to see it in graph form. Via the Center for Substance Abuse Research (CESAR)…
Marijuana Distribution Relies Primarily on Friends and Family
*Data was taken from the 2001 National Household Survey on Drug Abuse (since renamed the National Survey on Drug Use and Health) marijuana market survey questions.
I think the point here is that efforts to attack marijuana through criminal enforcement are doomed to failure and also inevitably cause tensions between citizens and law enforcement.