"In both 2002 and 2005, about 5% of stopped drivers were searched by police during the traffic stop. The 5% includes searches of the vehicle only, the driver only, and both the vehicle and the driver.

"In both years, male drivers were more likely than female drivers to be searched by police during a traffic stop.

"In 2005 black (9.5%) and Hispanic (8.8%) motorists stopped by police were searched at higher rates than whites (3.6%). The likelihood of experiencing a search did not change for whites, blacks, or Hispanics from 2002 to 2005."

Source

Durose, Matthew R., Smith, Erica L., and Langan, Patrick A., PhD, "Contacts Between Police and the Public, 2005," NCJ215243, US Dept. of Justice, Bureau of Justice Statistics, April 2007.