foreign currency transaction gains ( losses ) foreign currency transaction gains ( losses ) in millions were as follows: .
in 2017 what percentage of foreign currency transaction gains were attributable to mexico?
total ( 1 ) $ 42 $ ( 15 ) $ 106 _____________________________ ( 1 ) includes gains of $ 21 million , $ 17 million and $ 247 million on foreign currency derivative contracts for the years ended december 31 , 2017 , 2016 and 2015 , respectively . the company recognized net foreign currency transaction gains of $ 42 million for the year ended december 31 , 2017 primarily driven by transactions associated with vat activity in mexico , the amortization of frozen embedded derivatives in the philippines , and appreciation of the euro in bulgaria . these gains were partially offset by unfavorable foreign currency derivatives in colombia . the company recognized net foreign currency transaction losses of $ 15 million for the year ended december 31 , 2016 primarily due to remeasurement losses on intercompany notes , and losses on swaps and options at the aes corporation . this loss was partially offset in argentina , mainly due to the favorable impact of foreign currency derivatives related to government receivables . the company recognized net foreign currency transaction gains of $ 106 million for the year ended december 31 , 2015 primarily due to foreign currency derivatives related to government receivables in argentina and depreciation of the colombian peso in colombia . these gains were partially offset due to decreases in the valuation of intercompany notes at the aes corporation and unfavorable devaluation of the chilean peso in chile . income tax expense income tax expense increased $ 958 million to $ 990 million in 2017 as compared to 2016 . the company's effective tax rates were 128% ( 128 % ) and 17% ( 17 % ) for the years ended december 31 , 2017 and 2016 , respectively . the net increase in the 2017 effective tax rate was due primarily to expense related to the u.s . tax reform one-time transition tax and remeasurement of deferred tax assets . further , the 2016 rate was impacted by the items described below . income tax expense decreased $ 380 million to $ 32 million in 2016 as compared to 2015 . the company's effective tax rates were 17% ( 17 % ) and 42% ( 42 % ) for the years ended december 31 , 2016 and 2015 , respectively . the net decrease in the 2016 effective tax rate was due , in part , to the 2016 asset impairments in the u.s. , as well as the devaluation of the peso in certain of our mexican subsidiaries and the release of valuation allowance at certain of our brazilian subsidiaries . these favorable items were partially offset by the unfavorable impact of chilean income tax law reform enacted during the first quarter of 2016 . further , the 2015 rate was due , in part , to the nondeductible 2015 impairment of goodwill at dp&l and chilean withholding taxes offset by the release of valuation allowance at certain of our businesses in brazil , vietnam and the u.s . see note 19 2014asset impairment expense included in item 8 . 2014financial statements and supplementary data of this form 10-k for additional information regarding the 2016 u.s . asset impairments . see note 20 2014income taxes included in item 8 . 2014financial statements and supplementary data of this form 10-k for additional information regarding the 2016 chilean income tax law reform . our effective tax rate reflects the tax effect of significant operations outside the u.s. , which are generally taxed at rates different than the u.s . statutory rate . foreign earnings may be taxed at rates higher than the new u.s . corporate rate of 21% ( 21 % ) and a greater portion of our foreign earnings may be subject to current u.s . taxation under the new tax rules . a future proportionate change in the composition of income before income taxes from foreign and domestic tax jurisdictions could impact our periodic effective tax rate . the company also benefits from reduced tax rates in certain countries as a result of satisfying specific commitments regarding employment and capital investment . see note 20 2014income taxes included in item 8 . 2014financial statements and supplementary data of this form 10-k for additional information regarding these reduced rates. .