This should be a very obvious answer but I will humor you anyway.
If you have NAT pool 10.2.2.1-10.2.2.9 and user commuter is bound to 10.2.2.1, then the next user will draw one of the available NAT pool addresses not in use. Hence, the available pool is now 10.2.2.2-10.2.2.9.
--TH13
