Basically, there's this precipitous drop of marital satisfaction, which is closely aligned, we all know, with broader happiness, that doesn't rise again until your first child goes to college.

You can see that there is a fairly low rate of violence in the '50s and the '60s, then it soared upward for several decades, and began a precipitous decline, starting in the 1990s, so that it went back to the level that was last enjoyed in 1960.