Explanation

You begin by learning about football, which is by far the most popular sport in Europe. The word whereas then creates a contrast, so you need American fans to be evenly split between their many sports.

Measured is close, but doesn’t quite divide things up the way you need it to. Apportioned means “divided and allocated.”

Apportioned.
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this was a tough one. is this difference measured/apportioned always true?

@enzo26

yes it is
you measure things
while in apportioned you divide and allocate them

In Europe, football, otherwise known as soccer, it the most popular sport by several orders of magnitude, whereas in America, fandom is fairly evenly __________ among a few different sports.

Fact - 1 : In Europe, football is the most popular

Whereas - Contrastor

Fact - 2 : In America, fandom is evenly distributed among a few different sport.

My own word is distributed and the only word in this context which is synonymous with it is apportioned.

Apportioned means divided and shared.
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