It seems strange that my school (University of Waterloo) shows no people going to Google. Especially since there is a large Google office less than 5km from campus.
Yeah. UW feeds a lot to the local Seattle Facebook and Google offices, not just Microsoft. But I guess those satellite offices are a small portion of the larger companies.
The top-5 cutoff really throws it off. For the non-tech roles that are a lot less selective, pedigree isn't that important and geography will dominate. Where the data is actually interesting is in high-level roles where the competitive frame (for companies and for people) is national.
The graph only shows the 5 schools sending the most people to a given company, so it's far from comprehensive.