A recent study published in PLoS Medicine investigated drug use throughout the world.
This study presents novel data on the epidemiology drug use from representative, cross-national samples representing all regions of the world. Clear differences in drug use existed across the regions of the world, with the US estimated to have among the highest levels of both legal and illegal drug use among all countries surveyed. These differences may be closing in more recent birth cohorts, with higher levels of drug use seen among young adults across countries. Drug use is related to income, but does not appear to be simply related to drug policy, since countries with more stringent policies towards illegal drug use did not have lower levels of such drug use than countries with more liberal policies.
It may be a surprise that countries with a very suppressive drug policy report more cannabis and cocaine drug use than countries with a more 'liberal policy'. The Netherlands, for instance, often scorned at because of their 'all too soft' measures, has the lowest level of drug use in the countries surveyed.
So, why is it then that a seemingly flourishing world power like the US harbours most drug users in the world?