I take your point, but if we are going to measure how likely it is for an activity to lead to death then total deaths and total participants (or 'participant-ti

I take your point, but if we are going to measure how likely it is for an activity to lead to death then total deaths and total participants (or 'participant-time') are what we will look at. Most people would agree that driving has become a safer activity if you could show them that the number of injuries or fatalities per driver or distance travelled has been falling. The same is true for cycling.