College sports started as a source of university pride. But fan bases have grown past alumni bases, with teams serving as points of state and regional pride. Many fans of top teams didn't actually attend the schools they cheer for.

But how many? How much does it differ between national powers and state second fiddles? To try and see which power-conference fan bases include the most and least alumni, including graduates and non-graduates, we asked Facebook for help.

What percentage of those who "Like" each team's biggest official athletics Facebook page also list themselves as having attended that university? There are obvious imperfections to this methodology, including privacy settings, people who don't fill out their entire profiles, and some athletic departments simply being better at social media than others.

That said, a lot of the results line up with what you'd guess. The athletic department with the highest percentage of non-alumni Likes? Notre Dame, the self-proclaimed national brand, where only 4 percent of the people who like its biggest official Facebook page also list themselves as having attended.

There couldn't be a more predictable bottom nine than this, as most of these seem to have fans all around the country. All are the biggest college sports teams in sports-crazy states, and some are bigger than their local pro teams.

The bottom 10 is followed on the full list by Duke, LSU and Arkansas.

The strange inclusion at No. 10? Northwestern. As a Northwestern student, I have yet to meet anyone who both likes the Wildcats and didn't go to school there.

The top 10 is a more eclectic group, starting with the *other* giant school in Texas.

Despite its rapidly growing fan base, A&M alumni still make up a a majority of the Aggies' fan base, at least on Facebook. The rest of the list consists largely of teams from the smaller schools in their respective states or states that aren't crazy about college football.

This can be interpreted in two ways. For Texas fans, it's a point of pride that the Longhorns are the biggest brand in a huge state. For A&M fans, this means referring to UT fans as sidewalk alumni or T-shirt fans or just saying ...

Here's a quick look at a few big rivalries with interesting disparities:

And here are all the power-conference schools: