Are these only with current medical? Cuz I thought a license was for life, so not sure how we could drop by 50% unless we all die. Also, how does the FAA take into account dead people? Do they even know that you die?
The FAA statistics defines an active airman this way:
"An active airman is one who holds both an airmen certificate and a valid medical certificate. Airmen who must have a valid medical to exercise the privileges of their certificate are all airplane pilots, rotorcraft pilots, flight navigators, and flight engineers. Glider pilots are not required to have a medical examination but the numbers represent only those who had a valid medical certificate on record at the Aeronautical Center."
So far as I know, their database is not updated when a pilot dies. The medical certificate would eventually just expire, decreasing their count.