IATA ranking

http://www.iata.org/publications/pages/wats-passenger-carried.aspx

Scheduled passengers carried in 2012

Total (International + Domestic)

Rank / Airline / Thousands
1 Delta Air Lines 116,726
2 Southwest Airlines 112,234
3 United Airlines 92,619
4 American Airlines 86,335
5 China Southern Airlines 86,277
6 Ryanair 79,649
7 China Eastern Airlines 79,611
8 Lufthansa 64,393
9 US Airways 54,238
10 Air France 50,636


International :

Rank / Airline / Thousands
1 Ryanair 79,649
2 Lufthansa 50,877
3 easyJet 44,601
4 Emirates 37,733
5 Air France 33,693
6 British Airways 31,273
7 KLM 25,775
8 United Airlines 24,843
9 Air Berlin 23,179
10 Turkish Airlines 22,381


Ryanair does not fly domestic (ie inside Ireland) any more.

I thought FR had some domestic flights? The the 2 numbers cant be the same?

If I understand rightly, the IATA considers that domestic flights are flights flown inside a country by a carrier of that country.
For instance, a Milano-Roma is registered as a domestic flight only if flown by an Italian carrier.
Ryanair does not have any flight inside Ireland anymore.

http://www.ryanair.com/ie/news/iata-confirms-ryanair-is-the-world-s-favourite-airline

Ryanair, Europe’s only ultra-low cost carrier (ULCC), today (17 June) welcomed confirmation from IATA that Ryanair remains the world’s favourite airline after IATA’s 2012 World Airline Transport Statistics showed Ryanair once again carried more international passengers than any other airline.
 
Ryanair carried 79.6m international passengers last year, almost 29m more than second-placed Lufthansa (50.8m) and 35m more than third-placed EasyJet (44.6m).
 
Indeed, Ryanair carried more international passengers than:
·         EasyJet and British Airways combined (75.8m)
·         Air France, KLM , Iberia and Alitalia combined (79.3m)
·         Lufthansa and Air Berlin combined (74m)
·         and 8 times more passengers than Irish regional carrier Aer Lingus (9.6m)
 
Ryanair will carry more than 81.5m passengers this year.