Exactly none of the 80% receivers sold and later turned into functional firearms are reflected in the NICS numbers. This market has exploded in recent years, so there are more and more unregistered firearms with literally each passing day.
Defense Distributed has sold thousands of “Ghost Gunner” machines - and no one buys such a machine (at a cost of $1500+) to make just one 80% receiver into a 100% receiver.
Registered firearms? Does not compute. At least where I live.