The US has approximately 60 million movements a year and 15000 controllers (from faa.gov). Australia has approximately 4 million movements and 1000 controllers (from airservicesaustralia.com).
My calculator works out that if every single movement was provided some sort of service the ATC in both countries astoundingly works 4000 movements a year. Can't work out where I am losing the 116000 other movements for the hyper efficient US controllers.