Below is a useful map from the Economist on cocain trafficking in West Africa for the years 2005, 2006, 2007 and 2008.
The Economist writes:
WEST AFRICA has become an attractive trade route for Latin America’s cocaine smugglers in recent years. On June 8th two tonnes (2000kg) of the stuff (with an estimated street value of over $1 billion) were seized in the Gambia. While cocaine use in America has fallen by 50% over the last two decades, some European countries have seen consumption rates double or triple. Aided by its corruptible police and flimsy money-laundering laws, up to 150 tonnes of cocaine are estimated to pass through the region a year. In 2006 36% of the cocaine carriers caught in one network of European airports had come from west Africa. In 2008 this had dropped to 17%. Whether this reflects a drop in trade or the traffickers’ increasing skill in avoiding capture is unclear.