investment tax credits have been deferred by the regulated utility subsidiaries and are being amortized to income over the average estimated service lives of the related assets .the company recognizes accrued interest and penalties related to tax positions as a component of income tax expense and accounts for sales tax collected from customers and remitted to taxing authorities on a net basis .see note 14 2014income taxes for additional information .allowance for funds used during construction afudc is a non-cash credit to income with a corresponding charge to utility plant that represents the cost of borrowed funds or a return on equity funds devoted to plant under construction .the regulated utility subsidiaries record afudc to the extent permitted by the pucs .the portion of afudc attributable to borrowed funds is shown as a reduction of interest , net on the consolidated statements of operations .any portion of afudc attributable to equity funds would be included in other , net on the consolidated statements of operations .afudc is provided in the following table for the years ended december 31: .
[['', '2018', '2017', '2016'], ['allowance for other funds used during construction', '$ 24', '$ 19', '$ 15'], ['allowance for borrowed funds used during construction', '13', '8', '6']]
environmental costs the company 2019s water and wastewater operations and the operations of its market-based businesses are subject to u.s .federal , state , local and foreign requirements relating to environmental protection , and as such , the company periodically becomes subject to environmental claims in the normal course of business .environmental expenditures that relate to current operations or provide a future benefit are expensed or capitalized as appropriate .remediation costs that relate to an existing condition caused by past operations are accrued , on an undiscounted basis , when it is probable that these costs will be incurred and can be reasonably estimated .a conservation agreement entered into by a subsidiary of the company with the national oceanic and atmospheric administration in 2010 and amended in 2017 required the subsidiary to , among other provisions , implement certain measures to protect the steelhead trout and its habitat in the carmel river watershed in the state of california .the subsidiary agreed to pay $ 1 million annually commencing in 2010 with the final payment being made in 2021 .remediation costs accrued amounted to $ 4 million and $ 6 million as of december 31 , 2018 and 2017 , respectively .derivative financial instruments the company uses derivative financial instruments for purposes of hedging exposures to fluctuations in interest rates .these derivative contracts are entered into for periods consistent with the related underlying exposures and do not constitute positions independent of those exposures .the company does not enter into derivative contracts for speculative purposes and does not use leveraged instruments .all derivatives are recognized on the balance sheet at fair value .on the date the derivative contract is entered into , the company may designate the derivative as a hedge of the fair value of a recognized asset or liability ( fair-value hedge ) or a hedge of a forecasted transaction or of the variability of cash flows to be received or paid related to a recognized asset or liability ( cash-flow hedge ) .changes in the fair value of a fair-value hedge , along with the gain or loss on the underlying hedged item , are recorded in current-period earnings .the gains and losses on the effective portion of cash-flow hedges are recorded in other comprehensive income , until earnings are affected by the variability of cash flows .any ineffective portion of designated cash-flow hedges is recognized in current-period earnings. .

Question: by how much did allowance for other funds used during construction increase from 2016 to 2018?
Answer: 60%