Hmm...interesting. I'm not sure how the data reflects things like a core curriculum (where I read a lot of these) which is a general requirement...or maybe looks at the classes themselves which may be in one department or another. This could be further confused with common requirements being taught by professors in different fields, and so their syllabi might be classified differently? Curious.

Edit: the best way to investigate would be if it is all weighted by number of students or something, though that might be tough to do.