Sure, but how big is the total pool of female swimmers? If we assume that ability to swim (within a sex, for the sake of argument) follows a normal distribution, the denominator of "people that gave swimming a real try" is going to have a direct relationship with the capabilities of the best ever to try. This is completely ignoring funding, encouragement, and access, and strictly discussing the sheer number of women that have literally tried swimming at a young enough age to discover their talent and have the opportunity to become the best swimmer they possibly could if they have it.
It is easy to control for that, just look at the best man from a very small population.
For example, the fastest male swimmers in Iceland are still much faster than the fastest female swimmers in the world, and Iceland has 10 000 times less people than the world.
There aren't 10 000 times more men trying to become elite swimmers than women.
