"In 2008, many SEPs operated multiple sites, including fixed sites and mobile units. The total number of hours that clients were served by SEPs was summed for all sites operated by each program. The total number of scheduled hours per week ranged from <1 to 168 (mean: 29 hours per week; median: 24 hours per week). Delivery of syringes and other risk-reduction supplies to residences or meeting spots was reported by 41% of SEPs. A total of 111 (90%) SEPs allowed persons to exchange syringes on behalf of other persons (i.e., secondary exchange)."

Source

"Syringe Exchange Programs — United States, 2008," Morbidity and Mortality Weekly Report (Atlanta, GA: Centers for Disease Control, November 19, 2010) Vol. 59, No. 45, p. 1489.
http://www.cdc.gov/mmwr/pdf/w…