A sizable portion of those are from
post merger expansion 
brought you by America West Holdings

. Above the 9 330s and 10 767s you brought to the merger, fully a third of the additional 330 and 757 seats don't belong to the East.
Hello? There has been no merger expansion to date. Both sides are within one or two hulls of min fleet. Any new aircraft have been replacement aircraft. The company could have replaced East 737's with the new 321's and replaced West 737's with the 330's........but they didn't! Sorry. 🙁
I made 105k plus last year and laid over in domicile every trip. The entire month of July I had 33 hour layovers at home. Did another 33 hour this month at home.
Compare that to any 330 or 767 F/O. I bet I made more plus was gone half the time. (I get paid for cancellations.)
Ok, let's compare.....I made $104K plus last year and worked all of 44 days as a 75/76 reserve F/O (nine days in December alone. I know.....tough month). That's right....I had 321 days off at home (I live in base). I'm shooting for 36 days of work this year (one nice 3 day trip to Europe each month and I'm good) but at 330 rates thanks to the recent bids (should be around $117k).
Then why do I see so many East F/Os in uniforms acquired after the merger wearing four stripes? I'd say there's quite a complex out on the East about being a captain. You centered your whole DOH campaign on taking West captain seats.
You see many East F/O's in four stripe jackets because they had been Captains already, and at the time of the new uniform purchase, expected to be back in the left seat in relatively short order given the retirement schedule going forward. Then the NIC abomination came out and the age 60 rule change. If I had know it would be this long I would have purchased the new jacket with three stripes. I really don't give a damn how many stripes are on my jacket. I don't need to compensate for other areas. And we really don't want your West captain seat, or any West seat for that matter.