According to this website, the number of police getting killed is generally trending down.
I should point out that I have no idea where the site gets these numbers.
They purport to show LEO deaths since the Founding. Color me skeptical for accuracy in the 18th and 19th centuries.
Sorry, here’s the site.
http://www.nleomf.org/facts/officer-fatalities-data/year.html
According to this site, LEO is #10 for dangerous jobs in USA.
http://jobs.aol.com/articles/2013/11/12/the-15-most-dangerous-jobs-in-america/
Being a fisherman is more than 5x as likely to get you killed on the job.