[throwaway0a5e]

Those are also the only nights when people are out at all. People who have to be at work on weekday mornings aren't driving home from visiting their parents late on a Tuesday night, they're doing it late on a Saturday night. Yeah, it probably is alcohol but there's a lot of confounding factors.

[throwaway201103]

Indeed. A drunk driver alone on the road isn't really a danger to anyone but himself.