"The overall best estimates of criminal proceeds are close to US$2.1 trillion in 2009 or 3.6% of global GDP [Gross Domestic Product] (95% confidence interval: 2.7%-4.4%). If only typical transnational organized crime proceeds were considered (resulting from trafficking drugs, counterfeiting, human trafficking, trafficking in oil, wildlife, timber, fish, art and cultural property, gold, human organs and small and light weapons), the estimates would be around 1.5% of GDP. About half of these proceeds were linked to trafficking in drugs."

Source

"Estimating Illicit Financial Flows Resulting from Drug Trafficking and Other Transnational Organized Crimes," United Nations Office on Drugs and Crime (Vienna, Austria: 2011), p. 9.