I finally found the source for a very interesting statistic that I’d heard about.
The statistic, colloquially put: Travelling in an automobile is twice as dangerous as travelling by bicycle.
The long version, which I found on Aaron Tarfman’s excellent web site:
Per 1,000,000 exposure hours, the fatalities are
128.71 for skydiving.
1.07 for swimming.
0.47 for motoring.
0.26 for bicycling.
The source is Failure Analysis Associates Inc.
A conclusion one could draw from this is that if bicyclists need to wear helmets for their own safety, motor vehicle drivers and passengers really need to wear helmets — especially kids.
And skydiving to work is just plain bad judgment.