Thank you Swept..
I'm ex 737 and 757 and have spent the last 27 months in the Middle-East in a selection and recruitment role for one of the big carriers.. I hope that the following points help:
1 IMHO you should not read too much into certain airlines constantly advertising for new pilots; my former employer held thousands of applications on file but many applicants fail to maintain currency, class 1 etc
2 In any case, it was company policy to always attract the best candidates available...not just those whose CV was already on file. (LoCo operators please note, some of the very best candidates have not applied yet!)
Swept, I'm sorry but I think that you might be looking for data/info which has not been formally collated or analysed.. but the very best of luck all the same.