Lots and lots
If you want to quantify it properly then go to
https://www.lancasterbombers.net/for...ovement-cards/
It contains most of the Wellington movement cards, listing each unit that an aircraft belonged to from the day it was delivered until it was scrapped/lost. There are a few blocks in the late NC, NP series missing but you will have over 95% coverage.
Then you can find out where everyone was if that takes your fancy
Regards
Martin