{"pre_text": ["zimmer biomet holdings , inc .", "and subsidiaries 2017 form 10-k annual report notes to consolidated financial statements ( continued ) the following table provides a reconciliation of the beginning and ending balances of our foreign pension plan assets measured at fair value that used significant unobservable inputs ( level 3 ) ( in millions ) : ."], "post_text": ["we expect that we will have no legally required minimum funding requirements in 2018 for the qualified u.s .", "and puerto rico defined benefit retirement plans , nor do we expect to voluntarily contribute to these plans during 2018 .", "contributions to foreign defined benefit plans are estimated to be $ 17.0 million in 2018 .", "we do not expect the assets in any of our plans to be returned to us in the next year .", "defined contribution plans we also sponsor defined contribution plans for substantially all of the u.s .", "and puerto rico employees and certain employees in other countries .", "the benefits offered under these plans are reflective of local customs and practices in the countries concerned .", "we expensed $ 47.9 million , $ 42.5 million and $ 40.2 million related to these plans for the years ended december 31 , 2017 , 2016 and 2015 , respectively .", "15 .", "income taxes 2017 tax act : the president signed u.s .", "tax reform legislation ( 201c2017 tax act 201d ) on december 22 , 2017 , which is considered the enactment date .", "the 2017 tax act includes a broad range of provisions , many of which significantly differ from those contained in previous u.s .", "tax law .", "changes in tax law are accounted for in the period of enactment .", "as such , our 2017 consolidated financial statements reflect the immediate tax effect of the 2017 tax act .", "the 2017 tax act contains several key provisions including , among other things : 2022 a one-time tax on the mandatory deemed repatriation of post-1986 untaxed foreign earnings and profits ( e&p ) , referred to as the toll charge ; 2022 a reduction in the corporate income tax rate from 35 percent to 21 percent for tax years beginning after december 31 , 2022 the introduction of a new u.s .", "tax on certain off-shore earnings referred to as global intangible low-taxed income ( gilti ) at an effective tax rate of 10.5 percent for tax years beginning after december 31 , 2017 ( increasing to 13.125 percent for tax years beginning after december 31 , 2025 ) , with a partial offset by foreign tax credits ; and 2022 the introduction of a territorial tax system beginning in 2018 by providing a 100 percent dividend received deduction on certain qualified dividends from foreign subsidiaries .", "during the fourth quarter of 2017 , we recorded an income tax benefit of $ 1272.4 million , which was comprised of the following : 2022 income tax benefit of $ 715.0 million for the one-time deemed repatriation of foreign earnings .", "this is composed of a $ 1181.0 million benefit from the removal of a deferred tax liability we had recorded for the repatriation of foreign earnings prior to the 2017 tax act offset by $ 466.0 million for the toll charge recognized under the 2017 tax act .", "in accordance with the 2017 tax act , we expect to elect to pay the toll charge in installments over eight years .", "as of december 31 , 2017 , we have recorded current and non-current income tax liabilities related to the toll charge of $ 82.0 million and $ 384.0 million , respectively .", "2022 an income tax benefit of $ 557.4 million , primarily related to the remeasurement of our deferred tax assets and liabilities at the enacted corporate income tax rate of 21 percent .", "the net benefit recorded was based on currently available information and interpretations made in applying the provisions of the 2017 tax act as of the time of filing this annual report on form 10-k .", "we further refined our estimates related to the impact of the 2017 tax act subsequent to the issuance of our earnings release for the fourth quarter of 2017 .", "in accordance with authoritative guidance issued by the sec , the income tax effect for certain aspects of the 2017 tax act represent provisional amounts for which our accounting is incomplete , but with respect to which a reasonable estimate could be determined and recorded during the fourth quarter of 2017 .", "the actual effects of the 2017 tax act and final amounts recorded may differ materially from our current estimate of provisional amounts due to , among other things , further interpretive guidance that may be issued by u.s .", "tax authorities or regulatory bodies , including the sec and the fasb .", "we will continue to analyze the 2017 tax act and any additional guidance that may be issued so we can finalize the full effects of applying the new legislation on our financial statements in the measurement period , which ends in the fourth quarter of 2018 .", "we continue to evaluate the impacts of the 2017 tax act and consider the amounts recorded to be provisional .", "in addition , we are still evaluating the gilti provisions of the 2017 tax act and their impact , if any , on our consolidated financial statements as of december 31 , 2017 .", "the fasb allows companies to adopt an accounting policy to either recognize deferred taxes for gilti or treat such as a tax cost in the year incurred .", "we have not yet determined which accounting policy to adopt because determining the impact of the gilti provisions requires analysis of our existing legal entity structure , the reversal of our u.s .", "gaap and u.s .", "tax basis differences in the assets and liabilities of our foreign subsidiaries , and our ability to offset any tax with foreign tax credits .", "as such , we did not record a deferred income tax ."], "table": [["", "december 31 2017"], ["beginning balance", "$ 78.7"], ["gains on assets sold", "0.3"], ["change in fair value of assets", "3.8"], ["net purchases and sales", "5.2"], ["translation gain", "3.0"], ["ending balance", "$ 91.0"]], "table_ori": [["", "December 31, 2017"], ["Beginning Balance", "$78.7"], ["Gains on assets sold", "0.3"], ["Change in fair value of assets", "3.8"], ["Net purchases and sales", "5.2"], ["Translation gain", "3.0"], ["Ending Balance", "$91.0"]]}

Question: what was the change in defined contribution plans expenses for the u.s . between 2015 and 2016 in millions?
Evidence:
text_9: we expensed $ 47.9 million , $ 42.5 million and $ 40.2 million related to these plans for the years ended december 31 , 2017 , 2016 and 2015 , respectively .
Program: subtract(42.5, 40.2)
Answer:
str_answer: 2.3
exe_answer: 2.3