Airline passengers filed 11,445 complaints with the Transportation Department last year, an increase of more than one-fifth from 2011.

The rate of complaints per 100,000 passengers also rose, from 1.19 in 2011 to 1.43 last year.

A breakdown of that rate for the 14 largest U.S. carriers from a report being released Monday on airline quality by researchers at Purdue University and Wichita State University. The first rate is for 2012; the second for 2011.

-Air Tran: 0.91; 0.72

-Alaska: 0.51; 0.48

-American: 1.80; 1.46

-American Eagle: 1.27; 1.45

-Delta: 0.73; 1.23

-ExpressJet: 1.07

-Frontier: 1.05; 0.76

-Hawaiian: 0.89; 0.70

-JetBlue: 0.79; 1.08

-SkyWest: 0.88; 0.73

-Southwest: 0.25; 0.32

-United: 4.24; 2.21

-US Airways: 1.74; 1.91

-Virgin America: 1.50

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2011 rates were not available for ExpressJet and Virgin America.