pre-construction costs, interim dam safety measures and environmental costs and construction costs.
The authorized costs were being recovered via a surcharge over a twenty-year period which began in October 2012.
The unrecovered balance of project costs incurred, including cost of capital, net of surcharges totaled $85 million and $89 million as of December 31, 2018 and 2017, respectively.
Surcharges collected were $8 million and $7 million for the years ended December 31, 2018 and 2017, respectively.
Pursuant to the general rate case approved in December 2018, approval was granted to reset the twenty-year amortization period to begin January 1, 2018 and to establish an annual revenue requirement of $8 million to be recovered through base rates.
Debt expense is amortized over the lives of the respective issues.
Call premiums on the redemption of longterm debt, as well as unamortized debt expense, are deferred and amortized to the extent they will be recovered through future service rates.
Purchase premium recoverable through rates is primarily the recovery of the acquisition premiums related to an asset acquisition by the Company’s utility subsidiary in California during 2002, and acquisitions in 2007 by the Company’s utility subsidiary in New Jersey.
As authorized for recovery by the California and New Jersey PUCs, these costs are being amortized to depreciation and amortization on the Consolidated Statements of Operations through November 2048.
Tank painting costs are generally deferred and amortized to operations and maintenance expense on the Consolidated Statements of Operations on a straight-line basis over periods ranging from five to fifteen years, as authorized by the regulatory authorities in their determination of rates charged for service.
As a result of the prepayment by American Water Capital Corp. , the Company’s wholly owned finance subsidiary (“AWCC”), of the 5.62% Series C Senior Notes due upon maturity on December 21, 2018 (the “Series C Notes”), 5.62% Series E Senior Notes due March 29, 2019 (the “Series E Notes”) and 5.77% Series F Senior Notes due December 21, 2022 (the “Series F Notes,” and together with the Series E Notes, the “Series Notes”), a make-whole premium of $10 million was paid to the holders of the Series Notes on September 11, 2018.
Substantially all of these early debt extinguishment costs were allocable to the Company’s utility subsidiaries and recorded as regulatory assets, as the Company believes they are probable of recovery in future rates.
Other regulatory assets include certain construction costs for treatment facilities, property tax stabilization, employee-related costs, deferred other postretirement benefit expense, business services project expenses, coastal water project costs, rate case expenditures and environmental remediation costs among others.
These costs are deferred because the amounts are being recovered in rates or are probable of recovery through rates in future periods.
Regulatory Liabilities Regulatory liabilities generally represent amounts that are probable of being credited or refunded to customers through the rate-making process.
Also, if costs expected to be incurred in the future are currently being recovered through rates, the Company records those expected future costs as regulatory liabilities.
The following table provides the composition of regulatory liabilities as of December 31:
## Table 0 ##
The following table provides the details of NRG's operating revenues:
## Table 1 ##
Energy revenue consists of revenues received from third parties for sales of electricity in the day-ahead and real-time markets, as well as bilateral sales.
It also includes energy sold through long-term PPAs for renewable facilities.
In addition, energy revenue includes revenues from the settlement of financial instruments and net realized trading revenues.
Capacity revenue consists of revenues received from a third party at either the market or negotiated contract rates for making installed generation capacity available in order to satisfy system integrity and reliability requirements.
Capacity revenue also includes revenues from the settlement of financial instruments.
In addition, capacity revenue includes revenues received under tolling arrangements, which entitle third parties to dispatch NRG's facilities and assume title to the electrical generation produced from that facility.
Retail revenue, representing operating revenues of NRG's retail businesses, consists of revenues from retail sales to residential, small business, commercial, industrial and governmental/institutional customers, as well as revenues from the sale of excess supply into various markets, primarily in Texas.
Mark-to-market for economic hedging activities includes asset-backed hedges that have not been designated as cash flow hedges and ineffectiveness on cash flow hedges.
Contract amortization revenue consists of the amortization of the intangible assets for net in-market C&I contracts established in connection with the acquisitions of Reliant Energy and Green Mountain Energy, as well as acquired power contracts, gas derivative instruments, and certain power sales agreements assumed at Fresh Start and Texas Genco purchase accounting dates related to the sale of electric capacity and energy in future periods.
These amounts are amortized into revenue over the term of the underlying contracts based on actual generation or contracted volumes.
Other revenues include revenues generated by the Thermal Business consisting of revenues received from the sale of steam, hot and chilled water generally produced at a central district energy plant and sold to commercial, governmental and residential buildings for space heating, domestic hot water heating and air conditioning.
It also includes the sale of high-pressure steam produced and delivered to industrial customers that is used as part of an industrial process.
Other revenues also consists of operations and maintenance fees, or O&M fees, construction management services, or CMA fees, sale of natural gas and emission allowances, and revenues from ancillary services.
O&M fees consist of revenues received from providing certain unconsolidated affiliates with services under long-term operating agreements.
CMA fees are earned where NRG provides certain management and oversight of construction projects pursuant to negotiated agreements such as for the GenConn, Cedar Bayou 4 and certain solar construction projects.
Ancillary services are comprised of the sale of energy-related products associated with the generation of electrical energy such as spinning reserves, reactive power and other similar products.
Other revenues also includes unrealized trading activities.
When developing new renewable and conventional power generation facilities, NRG typically secures long-term PPAs, which insulate the Company from commodity market volatility and provide future cash flow stability.
These PPAs are typically contracted with high credit quality local utilities and typically have durations from 10 years to as much as 25 years.
Commercial Operations Overview NRG seeks to maximize profitability and manage cash flow volatility through the marketing, trading and sale of energy, capacity and ancillary services into spot, intermediate and long-term markets and through the active management and trading of emissions allowances, fuel supplies and transportation-related services.
The Company's principal objectives are the realization of the full market value of its asset base, including the capture of its extrinsic value, the management and mitigation of commodity market risk and the reduction of cash flow volatility over time.
NRG enters into power sales and hedging arrangements via a wide range of products and contracts, including PPAs, fuel supply contracts, capacity auctions, natural gas derivative instruments and other financial instruments.
In addition, because changes in power prices in the markets where NRG operates are generally correlated to changes in natural gas prices, NRG uses hedging strategies that may include power and natural gas forward sales contracts to manage the commodity price risk primarily associated with the Company's coal and nuclear generation assets.
The objective of these hedging strategies is to stabilize the cash flow generated by NRG's portfolio of assets.
NRG also trades electric power, natural gas and related commodity and financial products, including forwards, futures, options and swaps, through its ownership of BETM, which is also an energy management service provider for primarily thirdparty generating assets.
Certain other NRG entities trade to a lesser extent, utilizing similar products as well as oil and weather products.
The Company seeks to generate profits from volatility in the price of electricity, capacity, fuels and transmission congestion by buying and selling contracts in wholesale markets under guidelines approved by the Company's risk management committee.
Coal and Nuclear Operations The following table summarizes NRG's U. S.  coal and nuclear capacity and the corresponding revenues and average natural gas prices and positions resulting from coal and nuclear hedge agreements extending beyond December 31, 2016 and through 2020 for the Company's Gulf Coast region:
## Table 2 ##
(a) Net coal and nuclear capacity represents nominal summer net MW capacity of power generated as adjusted for the Company's ownership position excluding capacity from inactive/mothballed units, see Item 2 - Properties for units scheduled to be deactivated.
(b) Forecasted generation dispatch output (MWh) based on forward price curves as of December 31, 2016, which is then divided by number of hours in a given year to arrive at MW capacity.
The dispatch takes into account planned and unplanned outage assumptions.
(c) Includes amounts under power sales contracts and natural gas hedges.
The forward natural gas quantities are reflected in equivalent GWh based on forward market implied heat rate as of December 31, 2016, and then combined with power sales to arrive at equivalent GWh hedged.
The coal and nuclear sales include swaps and delta of options sold which is subject to change.
For detailed information on the Company's hedging methodology through use of derivative instruments, see discussion in Item 15 - Note 5, Accounting for Derivative Instruments and Hedging Activities, to the Consolidated Financial Statements.
Includes inter-segment sales from the Company's wholesale power generation business to the retail business.
(d) Percentage hedged is based on total coal and nuclear sales as described in (c) above divided by the forecasted coal and nuclear capacity.
(e) Represents U. S.  coal and nuclear sales, including energy revenue and demand charges.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td>2018</td><td>2017</td></tr><tr><td>Income taxes recovered through rates</td><td>$1,279</td><td>$1,242</td></tr><tr><td>Removal costs recovered through rates</td><td>309</td><td>315</td></tr><tr><td>Postretirement benefit liability</td><td>209</td><td>33</td></tr><tr><td>Pension and other postretirement benefit balancing accounts</td><td>46</td><td>48</td></tr><tr><td>TCJA reserve on revenue</td><td>36</td><td>—</td></tr><tr><td>Other</td><td>28</td><td>26</td></tr><tr><td>Total regulatory liabilities</td><td>$1,907</td><td>$1,664</td></tr></table>
<table><tr><td></td><td colspan="5">Year Ended December 31,</td></tr><tr><td></td><td>2014</td><td>2013</td><td>2012</td><td>2011</td><td>2010</td></tr><tr><td></td><td colspan="5">(In millions)</td></tr><tr><td>Energy revenue</td><td>$7,130</td><td>$5,636</td><td>$3,738</td><td>$3,804</td><td>$4,063</td></tr><tr><td>Capacity revenue</td><td>2,109</td><td>1,860</td><td>765</td><td>750</td><td>840</td></tr><tr><td>Retail revenue</td><td>7,385</td><td>6,305</td><td>5,900</td><td>5,807</td><td>5,277</td></tr><tr><td>Mark-to-market for economic hedging activities</td><td>541</td><td>-542</td><td>-418</td><td>325</td><td>-199</td></tr><tr><td>Contract amortization</td><td>-13</td><td>-31</td><td>-97</td><td>-159</td><td>-195</td></tr><tr><td>Other revenues</td><td>556</td><td>355</td><td>260</td><td>342</td><td>361</td></tr><tr><td>Eliminations</td><td>-1,840</td><td>-2,288</td><td>-1,726</td><td>-1,790</td><td>-1,298</td></tr><tr><td>Total operating revenues</td><td>$15,868</td><td>$11,295</td><td>$8,422</td><td>$9,079</td><td>$8,849</td></tr></table>
<table><tr><td>Gulf Coast</td><td>2017</td><td>2018</td><td>2019</td><td>2020</td><td>AnnualAverage for2017-2020</td></tr><tr><td></td><td colspan="5">(Dollars in millions unless otherwise stated)</td></tr><tr><td>Net Coal and Nuclear Capacity (MW)<sup>(a)</sup></td><td>6,250</td><td>6,250</td><td>6,250</td><td>6,250</td><td>6,250</td></tr><tr><td>Forecasted Coal and Nuclear Capacity (MW)<sup>(b)</sup></td><td>4,959</td><td>4,411</td><td>4,119</td><td>4,198</td><td>4,422</td></tr><tr><td>Total Coal and Nuclear Sales (GWh)<sup>(c)</sup></td><td>39,002</td><td>19,624</td><td>8,471</td><td>7,653</td><td>18,687</td></tr><tr><td>Percentage Coal and Nuclear Capacity Sold Forward<sup>(d)</sup></td><td>90%</td><td>51%</td><td>23%</td><td>21%</td><td>46%</td></tr><tr><td>Total Forward Hedged Revenues<sup>(e)</sup></td><td>$1,429</td><td>$747</td><td>$429</td><td>$406</td><td>$—</td></tr><tr><td>Weighted Average Hedged Price ($ per MWh)<sup>(e)</sup></td><td>$36.63</td><td>$38.07</td><td>$50.68</td><td>$53.07</td><td>$—</td></tr><tr><td>Average Equivalent Natural Gas Price ($ per MMBtu)<sup>(e)</sup></td><td>$3.68</td><td>$3.91</td><td>$4.83</td><td>$4.99</td><td>$—</td></tr><tr><td>Gross Margin Sensitivities</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Gas Price Sensitivity Up $0.50/MMBtu on Coal and Nuclear Units</td><td>$1</td><td>$76</td><td>$124</td><td>$147</td><td>$—</td></tr><tr><td>Gas Price Sensitivity Down $0.50/MMBtu on Coal and Nuclear Units</td><td>$—</td><td>$-69</td><td>$-113</td><td>$-124</td><td>$—</td></tr><tr><td>Heat Rate Sensitivity Up 1 MMBtu/MWh on Coal and Nuclear Units</td><td>$53</td><td>$100</td><td>$91</td><td>$96</td><td>$—</td></tr><tr><td>Heat Rate Sensitivity Down 1 MMBtu/MWh on Coal and Nuclear Units</td><td>$-36</td><td>$-79</td><td>$-71</td><td>$-77</td><td>$—</td></tr></table>

Question: In the year with lowest amount of Forecasted Coal and Nuclear Capacity, what's the increasing rate of Total Coal and Nuclear Sales?
Answer: -0.09656
Reasoning program: subtract(7653,8471), divide(#0,8471)