250,000 miles is a small number when talking about average drivers, let alone professional. My mother has driven atleast 200,000 miles in her life and never been on an accident. Ive done 100,000 miles on a motorcycle with only two hair raising close calls, and bikes are 60x more dangerous than cars mile for mile.

I don't think you can really get any significant data from 250,000 miles because most people don't wreck in 250,000 miles, especially professionals.