During our small business class we had a trip to the library and looked at various databases and on-line resources.
One interesting place to look is
ReferenceUSA
If a clown goes into legitimate business through the appropriate (government regulated) channels like having a business license and paying taxes etc. They may be listed here.
The NAICS [North American Industry Code System] number for our profession is 71151003. It does not have its own number per se, but counts for a broader category of Independent Artists, Writers, & Performers.
HOWEVER,
I had to log into my local libraries system and THEY paid for the access to the database.
I found 42 Michigan Clowns listed, 26 Oregon Clowns listed, and 41 Washington Clowns.