Dear Ms. Johnson,
Thank you for posting your request on History Hub!
We searched the Office of Personnel Management (OPM) located the Historical Federal Workforce Tables for 1940 to 2014 that may be of use to compile the data you seek. We also suggest that you utilize OPM’s online tool, FedScope, that provides access to data regarding federal employment.
The report of the Congressional Research Services titled Federal Workforce Statistics Sources: OPM and OMB includes employment data from 2014 to 2020.
We hope this is helpful. Best of luck in your research!