As to the baseline rate, the baseline rate for police reported accidents in the US is 1 per ~500k miles and fatalitys is 1 per ~80M miles [1]. That is approximately 1 per 30 years of driving and 1 per 5,000 years of driving, respectively using the reported average of ~15,000 miles per year per driver.
As to the availability of FSD data, you can see my other comment:
https://news.ycombinator.com/item?id=36181877
[1] https://cdan.nhtsa.gov/tsftables/National%20Statistics.pdf