**The answer is d:
15,000 person-years of cycling per fatality.
**The Cyclist's Touring Club has about 60,000 members.
On average, there are about 3 to 5 member fatalities per year.
That means, if the average CTC member rides 15,000 years, he'll reach a
50% chance of a fatal bike accident.
(For less enthusiastic cyclists in Britain, a similar computation gives
roughly the same answer.) ^{7}

So even in Britain, where cycling is more dangerous per hour than motoring, it seems it's not very dangerous in any absolute sense.