According to Ret. Lt. Col. Dave Grossman, "We're living in the most violent times in peacetime history. The murder rate in America, since 1957, has approximately doubled."
He goes on to quickly speak about violent crime rate vs. murder rate and the influence of medical technology. He continues, however, that the murder rate actually misrepresents the problem because medical technology saves evermore lives. Grossman makes the argument of what we should be looking at is the rate in which people are trying to kill one another.
The aggravated assault rate has gone from ±60 per 100,000 (in 1957) to over 440 per 100,000 (in the middle of this decade).
The talk starts at the 2:40 mark. It's worth a listen.