The core of the problem is the Michigan public school system is not producing enough high quality raw material for UM. For example, in 2006, the average ACT was 21.5. It dropped to about 19.6 and as of 2016 rose to 20.5. In 2010, only about 3% of the graduating HS class scored 30 or more on the ACT. By 2016 it had risen to 5%, which is an encouraging trend but still is not keeping up with the scores of OOS students applying. Only about 1% of the Michigan HS class scored 33 or above, which is the 75th percentile at UM where chance of admission is very high for in-state students.
So Michigan is faced with maintaining quality without an adequate supply of in-state students and insufficient support from the State of Michigan. If current trends continue, and the quality of students continue to improve and we should see the raw in-state numbers start to ratchet up a bit. With the increase in enrollment and dorm capacity I don’t see the percentages changing much.