Doug,
It shouldn't be difficult to find out the exact number of rounds per year at the course you reference.
I'd appreciate it if you'd inquire.
But, let's accept the 20,000 you indicated.
That's $ 500,000 per year..
I can't speak for club and green budget's in the area you reference, but, I'm hard pressed to think that a course can be reasonably maintained in the Midwest on $ 500,000 per year.
What do you think ?
In the Metropolitan NY area and in South Eastern Florida, between $ 1,000,000 and $ 2,000,000 would seem to be the norm for 18 holes.