net revenues include $ 3.8 billion in 2017 and $ 739 million in 2016 related to the sale of rrps , mainly driven by japan .these net revenue amounts include excise taxes billed to customers .excluding excise taxes , net revenues for rrps were $ 3.6 billion in 2017 and $ 733 million in 2016 .in some jurisdictions , including japan , we are not responsible for collecting excise taxes .in 2017 , approximately $ 0.9 billion of our $ 3.6 billion in rrp net revenues , excluding excise taxes , were from iqos devices and accessories .excise taxes on products increased by $ 1.1 billion , due to : 2022 higher excise taxes resulting from changes in retail prices and tax rates ( $ 4.6 billion ) , partially offset by 2022 favorable currency ( $ 1.9 billion ) and 2022 lower excise taxes resulting from volume/mix ( $ 1.6 billion ) .our cost of sales ; marketing , administration and research costs ; and operating income were as follows : for the years ended december 31 , variance .
[['( in millions )', 'for the years ended december 31 , 2017', 'for the years ended december 31 , 2016', 'for the years ended december 31 , $', '% (  % )'], ['cost of sales', '$ 10432', '$ 9391', '$ 1041', '11.1% ( 11.1 % )'], ['marketing administration and research costs', '6725', '6405', '320', '5.0% ( 5.0 % )'], ['operating income', '11503', '10815', '688', '6.4% ( 6.4 % )']]
cost of sales increased by $ 1.0 billion , due to : 2022 higher cost of sales resulting from volume/mix ( $ 1.1 billion ) , partly offset by 2022 lower manufacturing costs ( $ 36 million ) and 2022 favorable currency ( $ 30 million ) .marketing , administration and research costs increased by $ 320 million , due to : 2022 higher expenses ( $ 570 million , largely reflecting increased investment behind reduced-risk products , predominately in the european union and asia ) , partly offset by 2022 favorable currency ( $ 250 million ) .operating income increased by $ 688 million , due primarily to : 2022 price increases ( $ 1.4 billion ) , partly offset by 2022 higher marketing , administration and research costs ( $ 570 million ) and 2022 unfavorable currency ( $ 157 million ) .interest expense , net , of $ 914 million increased by $ 23 million , due primarily to unfavorably currency and higher average debt levels , partly offset by higher interest income .our effective tax rate increased by 12.8 percentage points to 40.7% ( 40.7 % ) .the 2017 effective tax rate was unfavorably impacted by $ 1.6 billion due to the tax cuts and jobs act .for further details , see item 8 , note 11 .income taxes to our consolidated financial statements .we are continuing to evaluate the impact that the tax cuts and jobs act will have on our tax liability .based upon our current interpretation of the tax cuts and jobs act , we estimate that our 2018 effective tax rate will be approximately 28% ( 28 % ) , subject to future regulatory developments and earnings mix by taxing jurisdiction .we are regularly examined by tax authorities around the world , and we are currently under examination in a number of jurisdictions .it is reasonably possible that within the next 12 months certain tax examinations will close , which could result in a change in unrecognized tax benefits along with related interest and penalties .an estimate of any possible change cannot be made at this time .net earnings attributable to pmi of $ 6.0 billion decreased by $ 932 million ( 13.4% ( 13.4 % ) ) .this decrease was due primarily to a higher effective tax rate as discussed above , partly offset by higher operating income .diluted and basic eps of $ 3.88 decreased by 13.4% ( 13.4 % ) .excluding .

Question: what is the percentage increase in interest expense?
Answer: 2.6%