Common-sized income statements Delta Air Lines, Inc. (DAL) provides cargo and passenger services throughout the world. The following common-sized income statements for Years 1 and 2 were adapted from recent financial statements of Delta. Delta Air Lines, Inc. Common-Sized Income Statement Increase Year 2 (Decrease) Year 1 Revenue 100.0 % 100.0 % n/a Operating expenses: Fuel (12.9) % (13.9) % 1.0 % Aircraft related (24.8) (25.7) 0.9 Selling and general (39.8) (40.1) 0.3 Other expenses (5.0) (5.5) 0.5 Total operating expenses (82.5) % (85.2) % 2.7 % Operating income 17.5 % 14.8 % (2.7) % Southwest Airlines Co. (LUV) provides passenger services throughout the United States, Mexico, Jamaica, The Bahamas, Aruba, and the Dominican Republic. The following common-sized income statements for Years 1 and 2 were adapted from recent financial statements of Southwest. Southwest Airlines Co. Common-Sized Income Statement Increase Year 2 (Decrease) Year 1 1 100.0 % % Revenue 100.0 % n/a Operating expenses: Fuel (17.9) % (18.6) % 0.7 % Aircraft related (18.1) (17.5) (0.6) Selling and general (33.3) (34.6) 1.3 Other expenses (12.3) (12.7) 0.4 Total operating expenses (81.6) % (83.4) % 1.8 % Operating income 18.4 % 16.6 % (1.8) % Compare and comment on the operating results of Delta and Southwest. Southwest's operating income as a percent of revenue by 1.8% compared to Delta's appear to be attributable to one item in particular. Southwest's to its percentage in operating income. Delta's combined increase in in operating income. of 2.7%. The difference in operating results in selling and general expenses of 1.3% was the major contributing factor expenses of 1.9% was the major contributing factor to its