From a post by Paul Krugman at the New York Times that links to this post at Crooked Timber, written by Kieren Healy.

 The  terrible events in Colorado this morning prompted me to update an old post about comparative death rates from assault across different societies. The following figures are from the OECD for deaths due to assault per 100,000 population from 1960 to the present. As before, the most striking features of the data are (1) how much more violent the U.S. is than other OECD countries (except possibly Estonia and Mexico, not shown here), and (2) the degree of change—-and recently, decline—-there has been in the U.S. time series considered by itself. Note that “assault” as a cause of death does not distinguish the mechanism of death (gunshot, stabbing, etc). If anyone knows of a similar time series for homicides specifically, let me know.

Beezer here.  As is often the case I begin with economist’s view, then from that site scroll over to New York Times economics columnist Paul Krugman, who then points me towards the Crooked Timber post by Healy.   The internet is truly an amazing place, particularly useful once you’ve sorted out who you can trust from the trolls and their propaganda sites.  That takes a while.