Except for Ohio State winning the natty in 2014, all of the other national champions going all the way back to 2006 have been southeastern teams (either SEC teams or teams geographically in the southeast like Clemson and Florida State). You could count 2005 if you count Texas as being in the southeast.
So of the past 15 national champions, the southeast has won 14 and the entire rest of the country: 1.
By the way, my state alone has won most of the past dozen national championships (6 for Bama and 1 for Auburn = 7 out of 12). College football really is a southern thing. The rest of the country just doesn't get it like we do.
Do notice that two of the new Big 12 teams are in the Southeast (Central Florida, Houston), and a third is the best team in Ohio as of late (Cincinnati). Not that I expect any of them to win a national championship any time soon.
Now that you bring up the subject to my mind: WTF happened to Nebraska?