Table 2.

Prevalence [95% CI] of any past-year marijuana use before and after legalization from National Survey on Drug Use and Health (NSDUH) and National Alcohol Survey (NAS)

NSDUH, Washington State
2009–2010 combined	13.8% [12.0%, 16.0%]
2010–2011 combined	14.9% [12.9%, 17.1%]
2011–2012 combined	15.3% [13.3%, 17.5%]
December 6, 2012, recreational legalization
2013–2014 combined	19.1% [16.9%, 21.4%]
2014–2015 combined	17.7% [15.5%, 19.9%]
NAS, Washington State
2009–2010 survey	19.5% [11.5%, 31.1%]
2014–2015 survey	28.6% [18.7%, 41.2%]