They sent out 900 questionnaires, advertised the survey in scholastic magazines and sent questionnaires to any school that asked for one. 162 colleges returned the survey. There are two UW campuses in that list.
Since they published the results for every school that returned a survey, and UW Madison isn't in that list, I assume they didn't return theirs. I have trouble thinking they might not have been sent one but I suppose it's possible.