The number of police killed in the line of duty rose sharply in 2016, driven by shootings of police around the country, most notably ambushes in Dallas and Baton Rouge, Louisiana.From Jan. 1 through Wednesday, 135 officers lost their lives. Some died in traffic accidents, but nearly half were shot to death.That's a 56 percent increase in shooting deaths over the previous year. Of the 64 who were fatally shot, 21 were killed in ambush attacks often fueled by anger over police use of force involving minorities."We've never seen a year in my memory when we've had an increase of this magnitude in officer shooting deaths," said Craig Floyd, president and chief executive of the National Law Enforcement Officers Memorial Fund.