About 7.3 % of Americans aged 18 or older used marijuana regularly in 2012 , survey finds . Marijuana is legal in 24 states , while many more allow medical use . Heroin use is up 70 % since 2007 , according to the survey .
About 7.3 % of Americans age 12 or older used marijuana regularly in 2012 , survey finds . Marijuana is legal in two states , while 20 more allow medical use . Heroin use is up 70 % since 2007 , according to the survey .