"In 2011, over 62.9 million U.S. residents age 16 or older, or 26% of the population, had one or more contacts with police during the prior 12 months […]. For about half (49%) of persons experiencing contact with police, the most recent contact was involuntary or police-initiated. In 2011, 86% of persons involved in traffic stops during their most recent contact with police and 66% of persons involved in street stops (i.e., stopped in public but not in a moving vehicle) believed that the police both behaved properly and treated them with respect during the contact. A greater percentage of persons involved in street stops (25%) than those pulled over in traffic stops (10%) believed the police had not behaved properly. Regardless of the reason for the stop, less than 5% of persons who believed the police had not behaved properly filed a complaint. The data in this report were drawn from the Bureau of Justice Statistics' (BJS) 2011 Police-Public Contact Survey (PPCS), a supplement to the National Crime Victimization Survey (NCVS), which collects information from a nationally representative sample of persons in U.S. households. The PPCS collects information on contact with police during a 12-month period. This report examines involuntary contacts with police, specifically those that occurred when the person was the driver of a motor vehicle (i.e., traffic stops) or when the person was stopped by the police while in a public place but not in a moving vehicle (i.e., street stops). It describes variations in perceptions of police behavior and police legitimacy during traffic and street stops. (For more information on how perceptions of police behavior and legitimacy were measured in this report, see survey questions on page 12.) All findings in this report are based on persons for whom the most recent contact in 2011 was in a street stop or as the driver in a traffic stop."
U.S. Bureau of Justice Statistics: http://www.bjs.gov/