United Airlines remained DIA’s dominant carrier in 2012, although its market share by passenger total slipped to 40.47 percent from 2011’s 42.96 percent, down 5.3 percent, the airport reported.

Southwest accounted for 23.62 percent of DIA passengers in 2012, up 9.3 percent from 2011.

Southwest’s total includes flights by AirTran Airways, which Southwest has acquired.