Just what the title says: what percentage of active players in Major League Baseball, the National Football League, and the National Basketball League come from a country other than the United States?
Also, what league has players from the greatest number of countries?
I don’t have hard numbers, but while we wait for them, my guess would be that MLB has the greatest of those three, followed by the NBA and then the NFL a very distant third. I’d guess well over 95% of NFL players are American, simply because it just isn’t played anywhere else.
The major US league that has the most player countries isn’t mentioned by your first statement. I think the NHL wins that one in a walk, though I don’t have the hard data.
I think MLB is far, far above the NHL in this regard. The NHL has the USA and Canada and a handful of European countries, but MLB has the Caribbean and Central America, Japan, South Korea, Taiwan, and Australia. I’d guess that there are twice as many countries represented in MLB than in the NHL.
My guess is that MLB has more countris represented, but the NHL still has a higher percentage of foreign born-players, even if you don’t count Canadians as “foreign.” However, that is just my general impression, I have no stats to back that up.
Puerto Rico is a special case which could be argued either way. However, I think for our purposes it makes sense to consider Puerto Rico “foreign” because it is considered a separate country for purposes of the Olympics and other international sports competiions and, more to the point, its sports system isn’t well integrated into the rest of the US.
NFL:
No luck. While it’s most popular in the US, Canadian football is pretty much the same thing for all intents and purposes, and NFL players have played in the CFL and vice versa.