There are no neat answers. Among the theories: As overall economic activity slows, more people who otherwise would be at work are unemployed and at home, and when they do travel they are not as likely to carry items of value, so burglaries and street robberies decline.
In the 1970s and early 1980s, when the economy went south crime rates went up. Inflation was high then, low now. Is that the difference? For the experts, it’s back to the drawing board.
All of the violent-crime categories decreased from 2008, as did all property crime categories.