Originally Posted by
bookworm
As a passenger boarding an aircraft, I care only about the likelihood of me surviving the journey. If I die, I don't care how many people die with me.
Which is why you are less interested in number of fatal accidents (ie accidents in which at least one fatality occurs), and you are concerned about the total number of fatalities per unit of measurement.
But either way, this is considerable drift from the question posed by the OP.