Rough numbers here:
- about 1 jump in 600 is a cutaway (actual numbers vary between 500-800).
- about 1 jump in 150000 is a fatality (actual numbers vary largely between 70000-250000).
So, there are about 250 cutaways for every fatality.
But this does NOT mean that a reserve chute has a failratio of 1/250!!! Nor does it mean that 1 cutaway in 250 leads to a fatality. Landing fatalities, no-pulls, are fatalities-without-cutaways.
I don't think anything can be concluded from the cutaway-to-fatals ratio.