( a ) the net change in the total valuation allowance for the years ended december 31 , 2018 and 2017 was an increase of $ 12 million and an increase of $ 26 million , respectively . deferred income tax assets and liabilities are recorded in the accompanying consolidated balance sheet under the captions deferred charges and other assets and deferred income taxes . there was a decrease in deferred income tax assets principally relating to the utilization of u.s . federal alternative minimum tax credits as permitted under tax reform . deferred tax liabilities increased primarily due to the tax deferral of the book gain recognized on the transfer of the north american consumer packaging business to a subsidiary of graphic packaging holding company . of the $ 1.5 billion of deferred tax liabilities for forestlands , related installment sales , and investment in subsidiary , $ 884 million is attributable to an investment in subsidiary and relates to a 2006 international paper installment sale of forestlands and $ 538 million is attributable to a 2007 temple-inland installment sale of forestlands ( see note 14 ) . a reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended december 31 , 2018 , 2017 and 2016 is as follows: .

Table:
in millions | 2018 | 2017 | 2016
balance at january 1 | $ -188 ( 188 ) | $ -98 ( 98 ) | $ -150 ( 150 )
( additions ) reductions based on tax positions related to current year | -7 ( 7 ) | -54 ( 54 ) | -4 ( 4 )
( additions ) for tax positions of prior years | -37 ( 37 ) | -40 ( 40 ) | -3 ( 3 )
reductions for tax positions of prior years | 5 | 4 | 33
settlements | 2 | 6 | 19
expiration of statutes oflimitations | 2 | 1 | 5
currency translation adjustment | 3 | -7 ( 7 ) | 2
balance at december 31 | $ -220 ( 220 ) | $ -188 ( 188 ) | $ -98 ( 98 )
if the company were to prevail on the unrecognized tax benefits recorded , substantially all of the balances at december 31 , 2018 , 2017 and 2016 would benefit the effective tax rate .
the company accrues interest on unrecognized tax benefits as a component of interest expense .
penalties , if incurred , are recognized as a component of income tax expense .
the company had approximately $ 21 million and $ 17 million accrued for the payment of estimated interest and penalties associated with unrecognized tax benefits at december 31 , 2018 and 2017 , respectively .
the major jurisdictions where the company files income tax returns are the united states , brazil , france , poland and russia .
generally , tax years 2006 through 2017 remain open and subject to examination by the relevant tax authorities .
the company frequently faces challenges regarding the amount of taxes due .
these challenges include positions taken by the company related to the timing , nature , and amount of deductions and the allocation of income among various tax jurisdictions .
pending audit settlements and the expiration of statute of limitations could reduce the uncertain tax positions by $ 30 million during the next twelve months .
the brazilian federal revenue service has challenged the deductibility of goodwill amortization generated in a 2007 acquisition by international paper do brasil ltda. , a wholly-owned subsidiary of the company .
the company received assessments for the tax years 2007-2015 totaling approximately $ 150 million in tax , and $ 380 million in interest and penalties as of december 31 , 2018 ( adjusted for variation in currency exchange rates ) .
after a previous favorable ruling challenging the basis for these assessments , we received an unfavorable decision in october 2018 from the brazilian administrative council of tax appeals .
the company intends to further appeal the matter in the brazilian federal courts in 2019 ; however , this tax litigation matter may take many years to resolve .
the company believes that it has appropriately evaluated the transaction underlying these assessments , and has concluded based on brazilian tax law , that its tax position would be sustained .
the company intends to vigorously defend its position against the current assessments and any similar assessments that may be issued for tax years subsequent to 2015 .
international paper uses the flow-through method to account for investment tax credits earned on eligible open-loop biomass facilities and combined heat and power system expenditures .
under this method , the investment tax credits are recognized as a reduction to income tax expense in the year they are earned rather than a reduction in the asset basis .
the company recorded a tax benefit of $ 6 million during 2018 and recorded a tax benefit of $ 68 million during 2017 related to investment tax credits earned in tax years 2013-2017. .

Question: unrecognized tax benefits change by what percent between 2017 and 2018?
Answer: 17%
Calculation: subtract(220, 188), divide(#0, 188)