19,592,303 NICS checks this past year.
160,474,702 since the system was implemented by
the FBI in 1998. There have probably been many more firearms sales, as
multiple firearms can be sold on each NICS check.
There are approximately 1.1 million police in the US, per 2008 numbers. Say for argument that there are 1.6 million now.
100 weapons per cop, and that's just since 1998.