The value of the illicit drug market is extremely difficult to estimate. The few serious attempts which have been made have resulted in widely varying figures.
A United Nations publication of 1998, "Economic and Social Consequences of Drug Abuse and Illicit Trafficking," states that:
"With estimates of $100 billion to $110 billion for heroin, $110 billion to $130 billion for cocaine, $75 billion for cannabis and $60 billion for synthetic drugs, the probable global figure for the total illicit drug industry would be approximately $360 billion. Given the conservative bias in some of the estimates for individual substances, a turnover of around $400 billion per annum is considered realistic."