Should be NICS.
Yeah, the POOL is based on the raw NICS number. NICS IS checked for Concealed Carry in many States.. So a place like Utah will show about 400X more checks than it should because it has one of the best reciprocal carry arrangements - and therefore people travel there to get their CC permit.
So this number is a combination.. its all NICS checks regardless of end purpose. It doesn't tell you how many guns are sold, it could be 3 per check. It could be a denial.
Its a proxy number for the number we really want to know..