If market #72 is acceptable as an answer to you, I can answer for KRKE as its program director.
There is a service called Mediabase which stations can subscribe to either by paying a monthly fee or by running a couple of minutes of barter advertising each day. It monitors the streams of every reporting station in the database and uses song-identifying software to log every "spin" that happens.
Subscribers can look at any individual stations' play history, sort by spin count, and made a good educated guess as to what that station's power and secondary rotations are, as well as see what newer songs are playing in lower rotation.
One feature Mediabase has is called Station Portfolio. In that, you can set up a custom report of only those stations that you want to see results for. So stations in the midwest, per your example, might only look at stations with the same format as theirs, in their part of the country.
For my purposes, I want to see primarily what songs are getting a lot of airplay nationally on Classic Hits, plus what songs are still getting a fair amount of play outside of the powers and secondaries. So my portfolio consists of about 35 stations in the top 40 markets, and another 50 in lesser markets. The system totals all the plays as well as breaking them out by station in separate columns, downloadble as an Excel file. The conclusions I draw from looking at those are pretty consistent; very little movement back and forth between categories every week.
By doing this, we benefit from the research done at the larger market stations and/or station groups by seeing what changes they make in rotation frequencies.
Hope that at least partially answers your question.