http://www.nationmaster.com/graph/lif_can_use-lifestyle-cannabis-use http://www.nationmaster.com/graph/lif_can_use-lifestyle-cann... Suggests it's 12.3% in the

http://www.nationmaster.com/graph/lif_can_use-lifestyle-cannabis-use http://www.nationmaster.com/graph/lif_can_use-lifestyle-cann... Suggests it's 12.3% in the US which I find more believable. The study you cited seems to ask "...EVER used". Which could just mean took one puff once when very drunk.