1094C Total Employee count - way off

Is anyone else seeing this? Our counts are thousands off. On the ACA Reporting Requirement EIT we set the Employee Count Date to Use =  L (Last of the month). So we are assuming this means count employees on the last day of the month.

For example - July

the 1094C is saying we have 13850 total employees.

But when I run a query to count our primary, non terminated assignments effective 31-jul-2015 I get 11857.  (1993 less)

Each month our employee count increases. It has us starting at 12888 in January and ending with 17282. We definitely did not increase our total employees by over 4000. I have us starting with 12766 and ending with 13890.