Well..lets see.
4 out of the top 5 have been the same since the beginning of the rankings (going up one or two spots, staying the same (Harvard, Stanford, Columbia and Yale has always been number 1)
But what's even more interesting is that only 14 schools have EVER received a top 10 spot (Cal, Columbia, Cornell, Duke, Georgetown, Harvard, NYU, Stanford, Chicago, Michigan, Penn, Virginia and of course, Yale), so I don't see what the difference is.
I think the difference goes in the middle to late ranked schools that are trying to get in the top 100.