Tom,
One of the first lessons in any course on statisics is the "Gambler's Fallacy." Every penny toss has a 50/50 chance of being heads or tails. This does not mean that if you toss a penny 100 times it will fall 50 heads and 50 tails. It means that every time you toss that penny it has a 50/50 chance of being one or the other. The only statistic that is 100% accurate is that if you are born there is a 100% chance that you will die some day. Any other statistic is based on the premiss that all relevant factors have been considered and they will not change.