A couple of years ago there were so many unassigned S80’s that just replacing them 1:1 with 737’s, that would be flying, was going to the same as a doubled digit (30???) increase in fleet size.

The fleet is being back filled. 64 n/b retirements in 2017-2019, 85 new AB/737 deliveries in the same period. Data subject to some change but hopefully fairly close.

Google ‘ MIT Airline Data Project’ and there’s a lot of data.

US/AA 2011 - 2016 block hour data -

2011. 3,361 (000’s)
2012. 3,339
2013. 3,448
2014. 3,602
2015. 3,479
2016. 3,495

4% more than 2011, 3% less than 2014. Half full vs half empty?