"an FOIA request"

The information for all airports with control towers is on the FAA web site as the Air Traffic Activity System.

The report for OSH, year 2013, does not include AirVenture, but shows that the ATCT handled 89,474 total operations.

Itinerant
45,547 general aviation
1,774 air taxi
465 military

Local
41,385 civil
303 military

The most recent FAA policy statement, from the negotiations over shutting down contract towers, was that an airport qualified for a control tower when there were 150,000 operations per year. This number is actually modified by "economic impact" factors. I will guess that EAA and AirVenture qualify as "economic impact" for the purposes of maintaining a full time tower presence.

If your airport has a control tower, you can look yourself up on the FAA web site and see what your official activity level is.

Best of luck,

Wes
N78PS