When I first jumped a round canopy in 1976, the average was 1 reserve ride for every 30 jumps.
When I started jumping for real in 1987, round canopies were no longer jumped.... everyone had "double square" rigs with ram-air main and reserve parachutes. I remember the average being reported as 1 reserve ride for every 500 jumps.
I have > 850 jumps from 1987 - 1997 and have never used my reserve. Skydiving is about the same level of danger as SCUBA. I remember the number being reported as 1 fatality for each 30,000 jumps.
If you subtract out the absolutely avoidable fatalities (unnecessary low turns trying for high performance landings, not following normal safety practices like gear checks), the number of fatalities is VERY low for what would be called an extreme sport.
Lisa wrote a very nice article about the risks....
look here.
It is absolutely the most fun thing you can do with your clothes on... You can skydive naked too!
Mark