This is a random thought. I'd be curious what the rate of 3 sports high school athletes are in the colder climates vs the warmer ones. I am making this up, but it would make sense that the further south you go, the easier it is to access year round competition in a sport if you are wanting to specialize. Up here in the cold, you have to go south to play any kind of competitive baseball past October or before April. I wonder if there is a correlation.