This might be a great Trivial Persuit question. But if you want to make money in poker, what you really need to estimate is the risk, your opponent has a higher flush, when you have a flush yourself, and you face a non-favourable action like a raise on the river. And this will depend on a lot of things like board texture, previous action, number of people seeing the flop and of course the strenght of your flush. A hand like 43s is much more likely to get overflushed than K9s. Its basically a hand reading situation, and if your opponents range consist of 80% better flushes, and you face a large raise, then you should fold, no matter how statistically likely or not a flush over flush situation might be in general.