Plant and Depreciation Utility Plant Utility plant is stated at original cost.
The cost of repairs and maintenance is charged to expense and the cost of betterments is capitalized.
The capitalized cost of additions to utility plant includes indirect costs such as engineering, supervision, payroll taxes, pensions, other benefits and an allowance for funds used during construction (AFUDC).
The original cost of property is charged to expense over the estimated useful lives of the assets.
Upon retirement, the original cost of property is charged to accumulated depreciation.
See Note R.  Rates used for AFUDC include the cost of borrowed funds and a reasonable rate of return on the Utilities’ own funds when so used, determined in accordance with regulations of the FERC or the state public utility regulatory authority having jurisdiction.
The rate is compounded semiannually, and the amounts applicable to borrowed funds are treated as a reduction of interest charges, while the amounts applicable to the Utilities’ own funds are credited to other income (deductions).
The AFUDC rates for CECONY were 4.4 percent, 1.6 percent and 4.0 percent for 2015, 2014 and 2013, respectively.
The AFUDC rates for O&R were 0.4 percent, 2.6 percent and 5.7 percent for 2015, 2014 and 2013, respectively.
The Utilities generally compute annual charges for depreciation using the straight-line method for financial statement purposes, with rates based on average service lives and net salvage factors.
The average depreciation rates for CECONY were 3.1 percent, 3.1 percent and 3.2 percent for 2015, 2014 and 2013, respectively.
The average depreciation rates for O&R were 3.0 percent, 2.9 percent and 2.8 percent for 2015, 2014 and 2013, respectively.
The estimated lives for utility plant for CECONY range from 5 to 85 years for electric and gas, 5 to 80 years for steam and 5 to 55 years for general plant.
For O&R, the estimated lives for utility plant range from 5 to 75 years for electric and gas and 5 to 50 years for general plant.
At December 31, 2015 and 2014, the capitalized cost of the Companies’ utility plant, net of accumulated depreciation, was as follows:
## Table 0 ##
Under the Utilities’ rate plans, the aggregate annual depreciation allowance in effect at December 31, 2015 was $1,110 million, including $1,050 million under CECONY’s electric, gas and steam rate plans that have been approved by the New York State Public Service Commission (NYSPSC).
Non-Utility Plant Non-utility plant is stated at original cost.
For Con Edison, non-utility plant consists primarily of the competitive energy businesses’ renewable electric production and gas storage.
For the Utilities, non-utility plant consists of land and conduit for telecommunication use.
Depreciation on these assets is computed using the straight-line method for financial statement purposes over their estimated useful lives, which range from 3 to 30 years.
Electric O&R’s results of electric operations for the year ended December 31, 2015 compared with the year ended December 31, 2014 is as follows:
## Table 1 ##
O&R’s electric sales and deliveries in 2015 compared with 2014 were:
## Table 2 ##
(a) O&R’s New York electric delivery revenues are subject to a revenue decoupling mechanism, as a result of which, delivery revenues are generally not affected by changes in delivery volumes from levels assumed when rates were approved.
O&R’s electric sales in New Jersey and Pennsylvania are not subject to a decoupling mechanism, and as a result, changes in such volumes do impact revenues.
(b) “Residential/Religious” generally includes single-family dwellings, individual apartments in multi-family dwellings, religious organizations and certain other not-for-profit organizations.
(c) Other electric operating revenues generally reflect changes in regulatory assets and liabilities in accordance with the company’s electric rate plan.
See Note B to the financial statements in Item 8.
(d) After adjusting for weather and other variations, electric delivery volumes in O&R’s service area decreased.0.9 percent in 2015 compared with 2014.
Operating revenues decreased $17 million in 2015 compared with 2014 due primarily to lower purchased power expenses ($28 million), offset in part by higher revenues from the New York electric rate plan ($19 million).
Purchased power expenses decreased $28 million in 2015 compared with 2014 due to a decrease in unit costs ($24 million) and purchased volumes ($4 million).
Other operations and maintenance expenses increased $5 million in 2015 compared with 2014 due primarily to the charge-off of certain regulatory assets ($4 million) and an increase in surcharges for assessments and fees that are collected in revenues from customers ($1 million).
Depreciation and amortization increased $4 million in 2015 compared with 2014 due primarily to higher electric utility plant balances.
Taxes, other than income taxes increased $1 million in 2015 compared with 2014 due primarily to higher property taxes and state and local revenue taxes.
Gas O&R’s results of gas operations for the year ended December 31, 2015 compared with the year ended December 31, 2014 is as follows:
Competitive Energy Businesses The competitive energy businesses’ results of operations for the year ended December 31, 2014 compared with the year ended December 31, 2013 is as follows:
## Table 3 ##
Operating revenues increased $148 million in 2014 compared with 2013, due primarily to higher wholesale and electric retail revenues ($125 million) and the impact of the LILO transactions ($27 million, see “Lease In/Lease Out Transactions” in Note J to the financial statements in Item 8).
Wholesale revenues increased $80 million in 2014 as compared to 2013 due to higher sales volume.
Electric retail revenues increased $45 million due to higher unit prices ($64 million), offset by lower sales volumes ($19 million).
Solar revenues decreased $14 million in 2014 as compared with 2013 primarily due to Con Edison Development’s sale of 50 percent of its membership interest in CED California Holdings Financing I, LLC (California Solar – see Note Q to the financial statements in Item 8).
Net mark-to-market values decreased $202 million in 2014 as compared with 2013, of which $206 million in losses are reflected in purchased power expenses and $4 million in gains are reflected in revenues.
Other revenues increased $6 million in 2014 as compared with 2013, due primarily to higher energy services revenues.
Purchased power expenses increased $227 million in 2014 compared with 2013 due primarily to changes in markto-market losses ($206 million) and higher unit prices ($64 million), offset by lower volumes ($43 million).
Gas purchased for resale increased $88 million due primarily to higher volumes.
Other operations and maintenance expenses increased $3 million due primarily to an increase in solar electric production projects in operation during 2014.
Depreciation and maintenance expense decreased $4 million due to Con Edison Development’s sale of 50 percent of its membership interest in California Solar (see Note Q to the financial statements in Item 8).
Taxes, other than income taxes increased $2 million due to an increase in sales and use taxes, property taxes and gross receipts tax.
Gain on sale of solar electric production projects was $45 million reflecting Con Edison Development’s sale of 50 percent of its membership interest in California Solar (see Note Q to the financial statements in Item 8).
Other Income (Deductions) Other income (deductions) increased $20 million in 2014 compared to 2013 primarily reflecting income from Con Edison Development’s solar investments that are accounted for under the equity method.
Net Interest Expense Net interest expense decreased $143 million in 2014 compared to 2013 due primarily to the impact of the LILO transactions.
See “Lease In/Lease Out Transactions” in Note J to the financial statements in Item 8.
Income Tax Expense Income taxes increased $34 million in 2014 compared with 2013 due primarily to higher income before income tax expense ($17 million) and a tax benefit in 2013 resulting from the acceptance by the IRS of the company’s claim for manufacturing tax deductions ($15 million).
Other For Con Edison, “Other” also includes intercompany eliminations relating to operating revenues and operating expenses.
The following table adjusts the revised diluted earnings per share for 2005 from the preceding table to reflect the approximate impact of using the non-substantive vesting period approach for these periods.

<table><tr><td></td><td colspan="2">Con Edison</td><td colspan="2">CECONY</td></tr><tr><td>(Millions of Dollars)</td><td>2015</td><td>2014</td><td>2015</td><td>2014</td></tr><tr><td>Electric</td><td></td><td></td><td></td><td></td></tr><tr><td>Generation</td><td>$459</td><td>$451</td><td>$459</td><td>$451</td></tr><tr><td>Transmission</td><td>3,045</td><td>2,956</td><td>2,833</td><td>2,744</td></tr><tr><td>Distribution</td><td>17,244</td><td>16,361</td><td>16,394</td><td>15,531</td></tr><tr><td>Gas (a)</td><td>5,698</td><td>5,006</td><td>5,196</td><td>4,530</td></tr><tr><td>Steam</td><td>1,849</td><td>1,795</td><td>1,849</td><td>1,795</td></tr><tr><td>General</td><td>1,758</td><td>1,650</td><td>1,592</td><td>1,498</td></tr><tr><td>Held for future use</td><td>77</td><td>76</td><td>65</td><td>65</td></tr><tr><td>Construction work in progress</td><td>1,003</td><td>1,031</td><td>922</td><td>971</td></tr><tr><td>Net Utility Plant</td><td>$31,133</td><td>$29,326</td><td>$29,310</td><td>$27,585</td></tr></table>
<table><tr><td></td><td colspan="2">For the Years Ended December 31,</td><td></td></tr><tr><td>(Millions of Dollars)</td><td>2015</td><td>2014</td><td>Variation</td></tr><tr><td>Operating revenues</td><td>$663</td><td>$680</td><td>$-17</td></tr><tr><td>Purchased power</td><td>210</td><td>238</td><td>-28</td></tr><tr><td>Other operations and maintenance</td><td>256</td><td>251</td><td>5</td></tr><tr><td>Depreciation and amortization</td><td>50</td><td>46</td><td>4</td></tr><tr><td>Taxes, other than income taxes</td><td>44</td><td>43</td><td>1</td></tr><tr><td>Electric operating income</td><td>$103</td><td>$102</td><td>$1</td></tr></table>
<table><tr><td></td><td colspan="4">Millions of kWh Delivered</td><td colspan="4">Revenues in Millions (a)</td></tr><tr><td></td><td colspan="2">For the Years Ended</td><td colspan="2"></td><td colspan="2">For the Years Ended</td><td colspan="2"></td></tr><tr><td>Description</td><td>December 31, 2015</td><td>December 31, 2014</td><td>Variation</td><td>PercentVariation</td><td>December 31, 2015</td><td>December 31, 2014</td><td>Variation</td><td>PercentVariation</td></tr><tr><td>Residential/Religious (b)</td><td>1,597</td><td>1,515</td><td>82</td><td>5.4%</td><td>$307</td><td>$307</td><td>—</td><td>—</td></tr><tr><td>Commercial/Industrial</td><td>802</td><td>812</td><td>-10</td><td>-1.2</td><td>124</td><td>136</td><td>$-12</td><td>-8.8%</td></tr><tr><td>Retail choice customers</td><td>3,237</td><td>3,240</td><td>-3</td><td>-0.1</td><td>213</td><td>207</td><td>6</td><td>2.9</td></tr><tr><td>Public authorities</td><td>100</td><td>102</td><td>-2</td><td>-2.0</td><td>10</td><td>12</td><td>-2</td><td>-16.7</td></tr><tr><td>Other operating revenues (c)</td><td>—</td><td>—</td><td>—</td><td>—</td><td>9</td><td>18</td><td>-9</td><td>-50.0</td></tr><tr><td>Total</td><td>5,736</td><td>5,669</td><td>67</td><td>1.2%(d)</td><td>$663</td><td>$680</td><td>$-17</td><td>-2.5%</td></tr></table>
<table><tr><td></td><td colspan="2">For the Years Ended December 31,</td><td></td></tr><tr><td>(Millions of Dollars)</td><td>2014</td><td>2013</td><td>Variation</td></tr><tr><td>Operating revenues</td><td>$1,244</td><td>$1,096</td><td>$148</td></tr><tr><td>Purchased power</td><td>1,088</td><td>861</td><td>227</td></tr><tr><td>Gas purchased for resale</td><td>115</td><td>27</td><td>88</td></tr><tr><td>Other operations and maintenance</td><td>108</td><td>105</td><td>3</td></tr><tr><td>Depreciation and amortization</td><td>19</td><td>23</td><td>-4</td></tr><tr><td>Taxes, other than income taxes</td><td>19</td><td>17</td><td>2</td></tr><tr><td>(Gain) on sale of solar electric production projects</td><td>-45</td><td>—</td><td>-45</td></tr><tr><td>Operating income (loss)</td><td>$-60</td><td>$63</td><td>$-123</td></tr></table>

Question: What is the difference between 2015 and 2014 's highest operating revenues? (in million)