interest expense .
what is the variation of the adjusted effective tax rate considering the years 2018-2019?
interest incurred increased $ .5 as interest expense associated with financing the lu'an joint venture was mostly offset by favorable impacts from currency , a lower average interest rate on the debt portfolio , and a lower average debt balance . capitalized interest decreased 31% ( 31 % ) , or $ 6.0 , due to a decrease in the carrying value of projects under construction , primarily driven by the lu'an project in asia . other non-operating income ( expense ) , net other non-operating income ( expense ) , net of $ 66.7 increased $ 61.6 , primarily due to lower pension settlement losses , higher non-service pension income , and higher interest income on cash and cash items . the prior year included pension settlement losses of $ 43.7 ( $ 33.2 after-tax , or $ .15 per share ) primarily in connection with the transfer of certain pension assets and payment obligations to an insurer for our u.s . salaried and hourly plans . in fiscal year 2019 , we recognized a pension settlement loss of $ 5.0 ( $ 3.8 after-tax , or $ .02 per share ) associated with the u.s . supplementary pension plan during the second quarter . net income and net income margin net income of $ 1809.4 increased 18% ( 18 % ) , or $ 276.5 , primarily due to impacts from the u.s . tax cuts and jobs act , positive pricing , and favorable volumes . net income margin of 20.3% ( 20.3 % ) increased 310 bp . adjusted ebitda and adjusted ebitda margin adjusted ebitda of $ 3468.0 increased 11% ( 11 % ) , or $ 352.5 , primarily due to positive pricing and higher volumes , partially offset by unfavorable currency . adjusted ebitda margin of 38.9% ( 38.9 % ) increased 400 bp , primarily due to higher volumes , positive pricing , and the india contract modification . the india contract modification contributed 80 bp . effective tax rate the effective tax rate equals the income tax provision divided by income from continuing operations before taxes . the effective tax rate was 21.0% ( 21.0 % ) and 26.0% ( 26.0 % ) in fiscal years 2019 and 2018 , respectively . the current year rate was lower primarily due to impacts related to the enactment of the u.s . tax cuts and jobs act ( the 201ctax act" ) in 2018 , which significantly changed existing u.s . tax laws , including a reduction in the federal corporate income tax rate from 35% ( 35 % ) to 21% ( 21 % ) , a deemed repatriation tax on unremitted foreign earnings , as well as other changes . as a result of the tax act , our income tax provision reflects discrete net income tax costs of $ 43.8 and $ 180.6 in fiscal years 2019 and 2018 , respectively . the current year included a cost of $ 56.2 ( $ .26 per share ) for the reversal of a benefit recorded in 2018 related to the u.s . taxation of deemed foreign dividends . we recorded this reversal based on regulations issued in 2019 . the 2019 reversal was partially offset by a favorable adjustment of $ 12.4 ( $ .06 per share ) that was recorded as we completed our estimates of the impacts of the tax act . this adjustment is primarily related to foreign tax items , including the deemed repatriation tax for foreign tax redeterminations . in addition , the current year rate included a net gain on the exchange of two equity affiliates of $ 29.1 , which was not a taxable transaction . the higher 2018 expense resulting from the tax act was partially offset by a $ 35.7 tax benefit from the restructuring of foreign subsidiaries , a $ 9.1 benefit from a foreign audit settlement agreement , and higher excess tax benefits on share-based compensation . the adjusted effective tax rate was 19.4% ( 19.4 % ) and 18.6% ( 18.6 % ) in fiscal years 2019 and 2018 , respectively . the lower prior year rate was primarily due to the $ 9.1 benefit from a foreign audit settlement agreement and higher excess tax benefits on share-based compensation. .