To anyone interested in such events I would highly recommend "The Black Swan" The Impact of the Highly Improbable by Nassim Nicholas Taleb.
It never amazes me what you can experience, if you are living in a large City or get involved with a large group of people. When I was doing National Service, I once drove to the Hospital, about twenty, 18yr olds suffering from "nocturnal enuresis" (http://en.wikipedia.org/wiki/Nocturnal_enuresis). It is a very uncommon event in adults <0.5%.
To be fair, The Black Swan doesn't talk about a black swan being rare. The point is that until black swans were discovered in Australia, everyone in the (civilized) world were completely convinced that swans could only be white. Black swans weren't rare, they were inconceivable because it was so far outside expectations that no one considered even the remote possibility of non-white swans.
The Black Swan doesn't talk about rare events, it talks about the danger of not considering that which is so highly improbable as to seem ridiculous, such as the possibility of non-white swans.
In other words, the frequency of black swans wasn't 1 in 1 million swans pre-discovery of Australia, it was zero.
I'm sure you know all of this but if you haven't read the book I do think it is worth your time.
It never amazes me what you can experience, if you are living in a large City or get involved with a large group of people. When I was doing National Service, I once drove to the Hospital, about twenty, 18yr olds suffering from "nocturnal enuresis" (http://en.wikipedia.org/wiki/Nocturnal_enuresis). It is a very uncommon event in adults <0.5%.