The Blue Jays national TV market would be bigger than any other team's TV market, so the necessarily really fair comparison would be the nationally televised games, if you want to point to the US' entire population size.
This Wiki article (link) has all the World Series ratings.
In recent years your looking at 10-16 million average viewers per game, and over 20 million average if it's a game 7.
So Canada seems more than twice as baseball hungry right now as the US in general.
Another decent comp would be the wild card games, because they were nationally televised and the Yankees were in one of them. I found this: