"Among the key findings of the report: 1) At the ten sites participating in the Arrestee Drug Abuse Monitoring (ADAM II) study, more than half of booked male arrestees tested positive for at least one illicit drug. Positive rates at the sites ranged from 56 percent in Mecklenburg County, North Carolina, to 82 percent in Cook County, Illinois. 2) Many arrestees tested positive for more than one illegal drug at the time of arrest. […] 3) The proportion of arrestees testing positive for cocaine declined significantly from either 2007 or 2008 to 2009 at eight of the ten sites. This may be an indication of a cocaine shortage, which is consistent with other cocaine indicators. 4) Methamphetamine rates remain highest in the West. Positive rates continue to decline in the markets with the highest prevalence."
White House: http://www.whitehouse.gov/