Big Ten enrollment from Wikipedia. All students, not just undergrads. I think Michigan might be under-reported here, other places have them around 42,000. Still, this list is close enough for our purposes.
1 Ohio State 56,064
2 Minnesota 52,557
3 Penn State 44,817
4 Michigan State 43,159
5 Indiana 42,464
6 Wisconsin 42,099
7 Illinois 41,918
8 Purdue 39,637
9 Michigan 37,197
10 Iowa 30,893
11 Nebraska 24,593
12 Northwestern 14,988
Looks like we are actually outperforming what one could expect based on this.
