A number I heard was 20% of flight crew. Of course this was just a 'coined' estimate. Even so, one would not just 'coin' a figure when it hasn't been estimated.
Assuming that figure were a good guess, then one would extrapolate from that statement with the following estimates.
400 pilots of which 200 are expats, 20% being the bottom 40 of the expat seniority.
Just guessing.