"With between 9.4 million and 28.2 million estimated past-year users in 2012, its use declined globally in the period 2010-2012, mainly in Western and Central Europe. Nevertheless, Oceania (2.9 per cent), North America (0.9 per cent) and Europe (0.5 per cent) remain regions with prevalence rates higher than the global average of 0.4 per cent."
Source
United Nations Office on Drugs and Crime, World Drug Report 2014 (United Nations publication, Sales No. E.14.XI.7), p. 50.
http://www.unodc.org/document…
