pre_text: table of contents notes to consolidated financial statements of american airlines group inc . information generated by market transactions involving comparable assets , as well as pricing guides and other sources . the current market for the aircraft , the maintenance condition of the aircraft and the expected proceeds from the sale of the assets , among other factors , were considered . the market approach was utilized to value certain intangible assets such as airport take off and landing slots when sufficient market information was available . the income approach was primarily used to value intangible assets , including customer relationships , marketing agreements , certain international route authorities , and the us airways tradename . the income approach indicates value for a subject asset based on the present value of cash flows projected to be generated by the asset . projected cash flows are discounted at a required market rate of return that reflects the relative risk of achieving the cash flows and the time value of money . the cost approach , which estimates value by determining the current cost of replacing an asset with another of equivalent economic utility , was used , as appropriate , for certain assets for which the market and income approaches could not be applied due to the nature of the asset . the cost to replace a given asset reflects the estimated reproduction or replacement cost for the asset , less an allowance for loss in value due to depreciation . the fair value of us airways 2019 dividend miles loyalty program liability was determined based on the weighted average equivalent ticket value of outstanding miles which were expected to be redeemed for future travel at december 9 , 2013 . the weighted average equivalent ticket value contemplates differing classes of service , domestic and international itineraries and the carrier providing the award travel . pro-forma impact of the merger the company 2019s unaudited pro-forma results presented below include the effects of the merger as if it had been consummated as of january 1 , 2012 . the pro-forma results include the depreciation and amortization associated with the acquired tangible and intangible assets , lease and debt fair value adjustments , the elimination of any deferred gains or losses , adjustments relating to reflecting the fair value of the loyalty program liability and the impact of income changes on profit sharing expense , among others . in addition , the pro-forma results below reflect the impact of higher wage rates related to memorandums of understanding with us airways 2019 pilots that became effective upon closing of the merger , as well as the elimination of the company 2019s reorganization items , net and merger transition costs . however , the pro-forma results do not include any anticipated synergies or other expected benefits of the merger . accordingly , the unaudited pro-forma financial information below is not necessarily indicative of either future results of operations or results that might have been achieved had the acquisition been consummated as of january 1 , 2012 . december 31 , ( in millions ) .
post_text: 5 . basis of presentation and summary of significant accounting policies ( a ) basis of presentation the consolidated financial statements for the full years of 2015 and 2014 and the period from december 9 , 2013 to december 31 , 2013 include the accounts of the company and its wholly-owned subsidiaries . for the periods prior to december 9 , 2013 , the consolidated financial statements do not include the accounts of us airways group . all significant intercompany transactions have been eliminated . the preparation of financial statements in accordance with accounting principles generally accepted in the united states ( gaap ) requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities , revenues and expenses , and the disclosure of contingent assets and liabilities at the date of the financial statements . actual results could differ from those estimates . the most significant areas .
table: December 31, 2013  (In millions)
table: Revenue $40,678
table: Net Income 2,526
question: Analyse this data from a financial earnings document. what were total operating expenses as a percentage of revenue in 2013?