There may be a natural ebb and flow at work. Some of the SM guys are getting fed up with the cost of running up front and switching to SRF. Some of the SRF guys are looking at the FSCCA car because it can be configured with and without the fenders. I guess people move in/out of IT for similar reasons.

Taking the cake is a big-bore ARRC winner I ran into at an oval racing school. He thought roundy-round looked fun and was going to try it for a while.

I'm not aware of any statistics; it's just casual observation. Does Topeka publish car counts?