@bclintonk When you look at the OOS enrollment at UMich, you need to pay attention to the population of those states too. The main reason to have more students coming from California and New York are mainly because of the population and applicant pool. The same reason for much less students from Wisconsin. While the higher OOS enrollment from Illinois is likely due to the proximity and poor financial aid of their in state flagship in addition to the population (UIUC).
I also want to restate that your OOS enrollment percentage at UMich is incorrect. OOS enrolled freshmen is only around 40%, not 60%.