Which aircraft type flies the most annual passenger-miles? Which aircraft type flies the most annual passenger-miles?

I understand there are over 4,000 737s in service. However, there are over 1,300 777s in service.

These each carry more passengers, and presumably spend more time in cruise, where miles are clocked up fastest. Is it possible the 777 flies the most annual passenger-miles?
Some heavies (747, 777, A380) fly short- to medium-haul in Asia and the Middle East. You could say they're stealing jobs from 737's and A320's.

Anyway, what I could find was for the US only.

Checking the Revenue Passenger Miles Total by Aircraft Type for 2016 on transtats.bts.gov we find—


All 737 variants: 153.2 billion
All 777 variants: 38.3 billion


Expanded:

Boeing 737-100/200         18,374,213
Boeing 737-200C                58,536
Boeing 737-300          6,609,070,471
Boeing 737-300LR              574,860
Boeing 737-400          1,484,593,783
Boeing 737-500            324,819,083
Boeing 737-700         44,485,736,725
Boeing 737-800         69,014,076,197
Boeing 737-900         18,203,949,655
Boeing 737-900ER       13,058,102,746
Boeing 777-200-        32,808,990,997
Boeing 777-300-         5,466,846,693


Top types with at least 10 billion pax miles:

Boeing 737-800                  69,014,076,197
Airbus Industrie A320-100/200   48,907,277,978
Boeing 737-700/700LR            44,485,736,725
Boeing 777-200ER/200LR/233LR    32,808,990,997
Airbus Industrie A321           28,492,821,887
Boeing 757-200                  26,182,350,221
Boeing 767-300/300ER            24,176,619,545
Airbus Industrie A319           22,087,734,671
Boeing 737-900                  18,203,949,655
DC9 Super 80/MD81/82/83/88      15,379,739,818
Boeing 737-900ER                13,058,102,746
Airbus Industrie A330-200       10,556,831,804


From this top list:


Single-aisle: 285.8 billion
Widebody: 67.5 billion


(Narrow- vs. widebody above is just in case you are wondering. Arbitrarily selecting top-x won't reveal much.)



Boeing's outlook for the future based on past- and current-trends sees the single-aisle market outgrowing the widebody.







I've tried to dig deeper, but it seems some 260 governments don't openly share those statistics, we'd need to hire an analyst firm for a worldwide view.