Here in WA, we have floods: 10-yr floods, 50-yr floods, 100-yr floods, 500-yr floods. The strange thing is that we've had three 100-yr floods in less than 20 yrs. Maybe it's just Ma Nature messing with the actuarys' minds.
Have you noticed that the Law of Averages never says 'never'?
If it happens once in 10,000 years and you're the one standing under the lightning bolt, you just feel different about the odds, somehow.