Out of 320 million people in the United States approximately 1,146 people were shot and killed by police last year. This statistic can be found on The Guardian website.
http://www.theguardian.com/us-news/ng-interactive/2015/jun/01/the-counted-police-killings-us-database#unknown-2016571
To look at things from a different perspective, 142 police officers died in the line of duty last year. Approximately 42 were killed from a firearm. Please read the link below.