The FBI’s annual Law Enforcement Officers Killed and Assaulted (LEOKA) report that was released earlier this week details in chilling narratives and statistics how 76 law enforcement officers were killed in the line of duty in 2013.
http://www.fbi.gov/news/news_blog/annual-officers-killed-report-more-than-a-tally-of-losses
Note: That is slightly more than one every 5 days (365 days / 76 killed).
Number of police officers in the U.S.: 780,000.
http://en.wikipedia.org/wiki/List_of_countries_by_number_of_police_officers
Therefore, the rate of killed in the line of duty / number of officers = 0.01% (one one-hundredth of one percent).