Table 9. Airline Domestic Unit Costs (Cents per Mile),,,,,,, Passenger Airlines by Group ,,,,,,, Ranked by 2nd Quarter 2006 Domestic Unit Costs ,,,,,,, (Domestic Operating Expenses per Available Seat Mile in cents),,,,,,, 2Q 2006 Rank,,2nd Quarter 2005 ,3rd Quarter 2005 ,4th Quarter 2005 ,1st Quarter 2006 ,2nd Quarter 2006 ,2nd Quarter Operating Expenses $(Millions) 1,Network Carriers,13.6,14,15,15,14.6,"16,318" 2,Regional Carriers,12.7,13.4,13.7,14,14.1,"2,250" 3,Low-Cost Carriers ,8.3,9.1,9.2,9.3,9.7,"4,546" ,21-Carrier Total,12.2,12.7,13.4,13.4,13.2,"23,114" "Source: Bureau of Transportation Statistics; Form 41, Schedule P1.2. T100; T2 Data",,,,,,,