Reference:
The way I see it, we're not really down at all, assuming the ones who entered on launch night were the definitive amount. Shabby walked....then we got THREE in - so we're two up. Now Caoimhe has walked and, I understand, Keely's not likely to return. So that would be three UNevicted people out and three in(even though one of the outs is also one of the ins. ) Thus we're even, calculating it that way.
But we always have 20 to 21 each series....