The problem is that you're comparing numbers from before Trump's presidency, but the understaffing of FAA ATCs goes all the way back to when the Reagan administration fired all ATCs to break up the union and forbade the FAA from rehiring any former union members.
The FAA has been playing catch up with training enough ATCs to meet demand ever since, which isn't helped by a sequence of bad decisions made regarding ATC training schools.
The FAA has been playing catch up with training enough ATCs to meet demand ever since, which isn't helped by a sequence of bad decisions made regarding ATC training schools.