Some interesting numbers on police killed in the line of duty appeared on the Hipcrime website, apparently taken wholly or partly from The Economist or perhaps from this FBI report.
Number of U.S. law enforcement officers killed as a result of criminal acts:
97 firemen died in 2013 in the U.S. Of course this is only part of the story. As would be expected, there was a high number of assaults of police, some of which caused injury.
Number of civilians shot and killed by police:
USA: 409 (in 2012, per FBI, plus one death by “other weapon”)
Japan + Britain + Germany = 8
The U.S. population is 17% larger, but the U.S.police killed 51 times more civilians.
British police fired their guns 3 times in 2012.
(For other data on police killings, check out this Sept. 3, 2014, newspaper article and this August 15th article in the Economist.).
As is always the case when reading numbers like this, one can't help but wonder what it is that makes the U.S. so prone to violence. My guess is that it's strongly linked to the TV shows people watch. In Korea, for example, the TV is filled with sappy (albeit well-written) romances. In Japan, amidst the endless silly quiz-shows full of hyper-feminine giggling women, there are plenty of feel-good shows (the Japanese equivalents of The Waltons). In these countries, violence tends to be portrayed as shocking and highly abnormal. In the U.S. media, Americans get this message that life is violent and that they must therefore also be hype-vigilant and ready to respond violently in any situation.