Source is the Wikimedia Commons:  This is a GIF image copy of that SVG/PNG image on the Commons.
Description: Lifetime prevalence of cannabis use among all adults (aged 15 to 64 years old) in nationwide surveys among the general population. For a table with the exact percentage for each nation see wikipedia:Adult lifetime cannabis use by country. For annual use see wikipedia:Annual cannabis use by country
Source data taken from EMCDDA (European Monitoring Centre for Drugs and Drug Addiction).  Survey year for each nation: Belgium (2004); Bulgaria (2005); Czech Rep. (2004); Denmark (2005); Germany (2003); Ireland (2002/03); Greece (2004); Spain (2005/06); France (2005); Italy (2005); Cyprus (2006); Latvia (2003); Lithuania (2004); Luxembourg (1998); Hungary (2003); Netherlands (2005); Austria (2004); Pland (2002); Portugal (2001); Romania (2004); Slovakia (2004); Finland (2005); Sweden (2006); UK (2004); Norway (2004).
Date: The map was made in January 2008
Author: User:Té y kriptonita on the Wikimedia commons.
Permission: See Wikimedia commons source. GNU Free Documentation license, Version 1.2 or any later version published by the Free Software Foundation.