This document produced by the Office of National Drug Control Policy outlines the flow of cocaine from South America to the United States. "For the second year in a row, the amount of cocaine departing South America continued to decrease. Nonetheless, drug trafficking organizations continued to move large quantities of cocaine. Data from the US Government interagency Consolidated Counterdrug Database that documents the movement of cocaine suggest a 12-20 percent decrease in the amount departing South America toward the US in 2009. However, production-based flow estimates, which calculate the amount of cocaine available to depart South America, showed a more modest 3 percent decrease. Estimates of potential cocaine production in the Andean region, expressed in metric tons, showed a significant decrease of 14.5 percent in 2008--the most recent year for which data was available. Furthermore, the purity of bulk cocaine shipments dropped to a record low of 76 percent, indicating extensive use of cutting agents to bulk up the cocaine in South America prior to departure and mitigating the impact of the decreased production on the gross volume of product available for export."
White House, Office of National Drug Control Policy: http://www.whitehousedrugpolicy.gov/