I have tracked #casa's annual report for a several years [table collated below], particularly since when flying you notice less and less radio calls or [except for Virgin, QANTAS and Jetstar], less aircraft in the air.
In the published data, #casa show a major discrepancy in the numbers. Here we see, looking at 2011, a missing 5,065 pilots. These are across the years and there is no #casa explanation.
What is worse, the "pilot numbers" do not gel at all with the medical certificates.
Just looking at 2011, the medical certificates [not corrected, by best guess for doubled up ones] is 22001, so we have a full missing 17, 371 pilots!!!
Must just be a discrepant table???