On Sun, 16 Aug 2015 11:49:26 -0400, Scott Dorsey wrote:

It's hard to get good data, though, when there are just so many
different inputs into the system.

The accident data for the USA is as reliable as any data you'll ever get,
particularly because the police report it, the insurance companies report
it, and in many states (such as mine), both individuals involved in even
a minor accident are required to report it.