This twitter thread gives some figures from the paper which is behind a paywall
This is the paper:
This shows how rare mutations are in DNA given the number of base pairs:
“Germline mutation rate:
~1 × 10-8 per base pair per generation.
Somatic mutation rate:
0.3 × 10-6 to 3 × 10-6 per base pair
(10 to 100x the germline rate)”