The Aeronautics segment generally includes fewer programs that have much larger sales and operating results than programs included in the other segments.
Due to the large number of comparatively smaller programs in the remaining segments, the discussion of the results of operations of those business segments focuses on lines of business within the segment rather than on specific programs.
The following tables of financial information and related discussion of the results of operations of our business segments are consistent with the presentation of segment information in Note 5 to the financial statements.
We have a number of programs that are classified by the U. S.  Government and cannot be specifically described.
The operating results of these classified programs are included in our consolidated and business segment results, and are subjected to the same oversight and internal controls as our other programs.
Aeronautics Our Aeronautics business segment is engaged in the research, design, development, manufacture, integration, sustainment, support, and upgrade of advanced military aircraft, including combat and air mobility aircraft, unmanned air vehicles, and related technologies.
Key Combat Aircraft programs include the F-35 Lightning II, F-16 Fighting Falcon, and F-22 Raptor fighter aircraft.
Key Air Mobility programs include the C-130J Super Hercules and the C-5M Super Galaxy.
Aeronautics provides logistics support, sustainment, and upgrade modification services for its aircraft.
Aeronautics’ operating results included the following:
## Table 0 ##
Net sales for Aeronautics increased by 8% in 2010 compared to 2009.
Sales increased in all three lines of business during the year.
The $800 million increase in Air Mobility primarily was attributable to higher volume on C-130 programs, including deliveries and support activities, as well as higher volume on the C-5 Reliability Enhancement and Re-engining Program (RERP).
There were 25 C-130J deliveries in 2010 compared to 16 in 2009.
The $179 million increase in Combat Aircraft principally was due to higher volume on F-35 production contracts, which partially was offset by lower volume on the F-35 SDD contract and a decline in volume on F-16, F-22 and other combat aircraft programs.
There were 20 F-16 deliveries in 2010 compared to 31 in 2009.
The $55 million increase in Other Aeronautics Programs mainly was due to higher volume on P-3 and advanced development programs, which partially were offset by a decline in volume on sustainment activities.
Net sales for Aeronautics increased by 6% in 2009 compared to 2008.
During the year, sales increased in all three lines of business.
The increase of $296 million in Air Mobility’s sales primarily was attributable to higher volume on the C-130 programs, including deliveries and support activities.
There were 16 C-130J deliveries in 2009 and 12 in 2008.
Combat Aircraft sales increased $316 million principally due to higher volume on the F-35 program and increases in F-16 deliveries, which partially were offset by lower volume on F-22 and other combat aircraft programs.
There were 31 F-16 deliveries in 2009 compared to 28 in 2008.
The $116 million increase in Other Aeronautics Programs mainly was due to higher volume on P-3 programs and advanced development programs, which partially were offset by declines in sustainment activities.
Operating profit for the segment decreased by 5% in 2010 compared to 2009.
A decline in operating profit in Combat Aircraft partially was offset by increases in Other Aeronautics Programs and Air Mobility.
The $149 million decrease in Combat Aircraft’s operating profit primarily was due to lower volume and a decrease in the level of favorable performance adjustments on the F-22 program, the F-35 SDD contract and F-16 and other combat aircraft programs in 2010.
These decreases more than offset increased operating profit resulting from higher volume and improved performance on F-35 production contracts in 2010.
The $35 million increase in Other Aeronautics Programs mainly was attributable to higher volume and improved performance on P-3 and advanced development programs as well as an increase in the level of favorable performance adjustments on sustainment activities in 2010.
The $19 million increase in Air Mobility operating profit primarily was due to higher volume and improved performance in 2010 on C-130J support activities, which more than offset a decrease in operating profit due to a lower level of favorable performance adjustments on C-130J deliveries in 2010.
The remaining change in operating profit is attributable to an increase in other income, net between the comparable periods.
Aeronautics’ 2010 operating margins have decreased when compared to 2009.
The operating margin decrease reflects the life cycles of our significant programs.
Specifically, Aeronautics is performing more development and initial production work on the F-35 program and is performing less work on more mature programs such as the F-22 and F-16.
Development and initial production contracts yield lower profits than mature full rate programs.
Accordingly, while net sales increased in 2010 relative to 2009, operating profit decreased and consequently operating margins have declined.
Noble Energy, Inc.
Supplemental Oil and Gas Information (Unaudited) 114 Proved Oil Reserves (Unaudited) The following reserves schedule was developed by our qualified petroleum engineers and sets forth the changes in estimated quantities of proved crude oil reserves:
## Table 1 ##
(1) Other International includes Israel, the North Sea, China and Argentina.
We sold our Argentina assets in 2008.
(2) The 2008 negative revisions within the US are primarily due to lower year-end prices (28 MMBbl), partially offset by the recording of NGLs which had previously been recorded in proved natural gas reserves.
The 2009 negative revisions within the US are primarily due to performance revisions, the majority of which related to Main Pass (10 MMBbl) and reclassifications of PUDs to probable reserves as a result of the SEC’s new five year development rule (5 MMBbl), partially offset by higher yearend prices (10 MMBbl).
The 2010 US revisions include the impacts of higher prices and additional NGLs booked in Wattenberg, partially offset by the reclassification of 16 MMBbls of PUD reserves to probable reserves, primarily in Wattenberg, as a result of the SEC's five year development rule.
The 2010 revisions to other international reserves are related to performance revisions in China and the North Sea.
(3) The 2008 increase in proved reserves includes 13 MMBbl in Wattenberg, primarily due to infill drilling activities, and 9 MMBbl in China.
The 2009 increase in proved reserves includes 20 MMBbl related to the ongoing development of Wattenberg, 11 MMBbl in the deepwater Gulf of Mexico for the Santa Cruz, Isabela and Swordfish fields, and 26 MMBbl in Equatorial Guinea for the Aseng field.
The 2010 increase in US proved reserves relates to continuing development of onshore assets, primarily in the Central DJ Basin.
The 2010 increase in Equatorial Guinea reserves includes 26 MMBbl for the Alen field.
(4) The 2010 increase relates to the Central DJ Basin asset acquisition.
See Note 3.
Acquisitions and Divestitures.
(5) We sold non-core, mature onshore US assets in the Mid-Continent and Illinois Basin in 2010 and our Argentina assets in 2008.
See Note 3.
Acquisitions and Divestitures.
(6) Equatorial Guinea production includes sales from the Alba field to the Alba LPG plant of 3 MBbl in each of 2010, 2009, and 2008.
Noble Energy, Inc.  Index to Financial Statements Notes to Consolidated Financial Statements 115 Note 5.
Asset Impairments Pre-tax (non-cash) asset impairment charges were as follows:
## Table 2 ##
2015 Asset Impairments During 2015, certain deepwater Gulf of Mexico, Eastern Mediterranean and Equatorial Guinea properties were written down to their estimated fair values using a discounted cash flow model.
The cash flow model included management’s estimates of future crude oil and natural gas production, commodity prices based on forward commodity price curves or contract prices as of the date of the estimate, operating and development costs, and discount rates.
Impairment charges of $481 million resulted from reductions in the forward crude oil prices as of December 31, 2015.
In addition, we recorded approximately $47 million of impairment primarily related to revisions in expected field abandonment and other costs for deepwater Gulf of Mexico and Eastern Mediterranean properties.
During fourth quarter 2015, we executed an agreement to divest our interest in the Alon A and Alon C offshore Israel licenses, which include the Karish and Tanin fields.
As a result, these assets were written down to expected proceeds less costs to sell, resulting in a $5 million impairment.2014 Asset Impairments As a result of declining crude oil prices at the end of 2014, we recorded impairment charges of $250 million related to certain onshore US and deepwater Gulf of Mexico properties.
During 2014, South Raton in the deepwater Gulf of Mexico was shut-in due to mechanical issues; therefore, we recorded additional impairment charges of $74 million for South Raton in fourth quarter 2014.
Additionally, the asset carrying values of certain crude oil and natural gas properties in the deepwater Gulf of Mexico and offshore Israel increased when we recorded associated increases in asset retirement obligations.
We determined that the recorded carrying values of some of these assets were not recoverable from future cash flows and recorded impairment expense of $51 million.
During third quarter 2014, we reclassified certain non-core properties as assets held for sale.
The assets were written down to expected proceeds less costs to sell, resulting in a $31 million impairment.
In March 2014, the operator of the MacCulloch North Sea field notified the working interest owners that expected field abandonment costs would be higher than originally projected, and that field abandonment would occur sooner than anticipated.
As a result of this new information, we adjusted the asset retirement obligation to reflect the updated estimate of abandonment costs and timing.
We assessed the asset for impairment and determined that it was impaired.2013 Asset Impairments We recorded impairments of the Mari-B field, due to natural field decline, and certain non-core, onshore US properties upon reclassification to assets held for sale.
The Mari-B field was written down to its estimated fair value using a discounted cash flow model, as described above.
The fair values of onshore US assets held for sale were based on anticipated sales proceeds less costs to sell.
See Note 13.
Fair Value Measurements and Disclosures.
Note 6.
Capitalized Exploratory Well Costs We capitalize exploratory well costs until a determination is made that the well has found proved reserves or is deemed noncommercial.
If a well is deemed to be noncommercial, the well costs are immediately charged to exploration expense as dry hole cost.
Other (Income) Expense Other (income) expense was as follows:
## Table 3 ##
See Item 8.
Financial Statements and Supplementary Data – Note 2.
Additional Financial Statement Information.
(Gain) Loss on Commodity Derivative Instruments (Gain) Loss on commodity derivative instruments is a result of mark-tomarket accounting.
Many factors impact our (gain) loss on commodity derivative instruments including: increases and decreases in the commodity forward price curves compared with our executed hedging arrangements; increases in hedged future volumes; and the mix of hedge arrangements between NYMEX WTI, Dated Brent and NYMEX HH commodities.
See Critical Accounting Policies and Estimates – Derivative Instruments and Hedging Activities, and Item 8.
Financial Statements and Supplementary Data – Note 8.
Derivative Instruments and Hedging Activities and Note 13.
Fair Value Measurements and Disclosures.
Interest Expense and Capitalized Interest Interest expense and capitalized interest were as follows:
## Table 4 ##
(1) Consolidated unit rates exclude sales volumes and costs attributable to equity method investees.
Interest expense prior to the reduction of capitalized interest increased in 2015 as compared with 2014.
The increase in interest expense is related to a full year of interest on senior debt issued in November 2014, as well as interest on senior notes assumed by us in the Rosetta Merger during third quarter 2015.
We drew down and repaid amounts under our Credit Facility for working capital purposes.
There were no other significant changes in our debt.
Interest expense prior to the reduction of capitalized interest increased in 2014 as compared with 2013.
Interest related to a full year of interest on senior debt issued in November 2013, as well as interest related to senior debt issued in November 2014 was offset by a reduction in interest related to repayment of an installment loan.
We drew down and repaid amounts under our Credit Facility for working capital purposes.
There were no other significant changes in our debt.
Interest capitalized in 2015 increased as compared with 2014.
The increase is primarily due to higher work in progress amounts related to major long-term projects in deepwater Gulf of Mexico, offshore West Africa, and offshore Israel, as well as expansion of midstream infrastructure in the DJ Basin.
Interest capitalized in 2014 decreased slightly as compared with 2013.
The decrease is due primarily to the completion of major projects at Alen and Tamar in 2013 offset by higher work in progress amounts related to major long-term projects onshore US and deepwater Gulf of Mexico.
Interest is capitalized on exploration and development projects using an interest rate equivalent to the average rate paid on long-term debt.
Capitalized interest is included in the cost of oil and gas assets and amortized with other costs on a unit-ofproduction basis.
The majority of the capitalized interest is related to long lead-time projects in the deepwater Gulf of Mexico, offshore West Africa and offshore Eastern Mediterranean.
See Item 8.
Financial Statements and Supplementary Data – Note 6.
Capitalized Exploratory Well Costs.
Other Non-operating (Income) Expense, Net Other non-operating (income) expense, net includes deferred compensation (income) expense, interest income and other (income) expense, net.
See Item 8.
Financial Statements and Supplementary Data – Note 2.
Additional Financial Statement Information.

<table><tr><td><i>(In millions)</i></td><td>2010</td><td>2009</td><td><i>2008</i></td></tr><tr><td>Net sales</td><td>$13,235</td><td>$12,201</td><td>$11,473</td></tr><tr><td>Operating profit</td><td>1,502</td><td>1,577</td><td>1,433</td></tr><tr><td>Operating margin</td><td>11.3%</td><td>12.9%</td><td>12.5%</td></tr><tr><td>Backlog at year-end</td><td>27,500</td><td>26,700</td><td>27,200</td></tr></table>
<table><tr><td></td><td colspan="4">Crude Oil, Condensate and NGLs (MMBbls)</td></tr><tr><td></td><td>United States</td><td>Equatorial Guinea</td><td>Other Int'l -1</td><td>Total</td></tr><tr><td>Proved Reserves as of:</td><td></td><td></td><td></td><td></td></tr><tr><td>December 31, 2007</td><td>207</td><td>82</td><td>40</td><td>329</td></tr><tr><td>Revisions of Previous Estimates-2</td><td>-10</td><td>1</td><td>-</td><td>-9</td></tr><tr><td>Extensions, Discoveries and Other Additions-3</td><td>16</td><td>-</td><td>11</td><td>27</td></tr><tr><td>Purchase of Minerals in Place-4</td><td>3</td><td>-</td><td>-</td><td>3</td></tr><tr><td>Sale of Minerals in Place-5</td><td>-</td><td>-</td><td>-7</td><td>-7</td></tr><tr><td>Production-6</td><td>-18</td><td>-8</td><td>-6</td><td>-32</td></tr><tr><td>December 31, 2008</td><td>198</td><td>75</td><td>38</td><td>311</td></tr><tr><td>Revisions of Previous Estimates-2</td><td>-5</td><td>-1</td><td>-</td><td>-6</td></tr><tr><td>Extensions, Discoveries and Other Additions-3</td><td>32</td><td>26</td><td>1</td><td>59</td></tr><tr><td>Purchase of Minerals in Place-4</td><td>1</td><td>-</td><td>-</td><td>1</td></tr><tr><td>Sale of Minerals in Place-5</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Production-6</td><td>-17</td><td>-8</td><td>-4</td><td>-29</td></tr><tr><td>December 31, 2009</td><td>209</td><td>92</td><td>35</td><td>336</td></tr><tr><td>Revisions of Previous Estimates-2</td><td>15</td><td>1</td><td>-5</td><td>11</td></tr><tr><td>Extensions, Discoveries and Other Additions-3</td><td>25</td><td>26</td><td>3</td><td>54</td></tr><tr><td>Purchase of Minerals in Place-4</td><td>23</td><td>-</td><td>-</td><td>23</td></tr><tr><td>Sale of Minerals in Place-5</td><td>-28</td><td>-</td><td>-</td><td>-28</td></tr><tr><td>Production-6</td><td>-19</td><td>-7</td><td>-5</td><td>-31</td></tr><tr><td>December 31, 2010</td><td>225</td><td>112</td><td>28</td><td>365</td></tr><tr><td>Proved Developed Reserves as of:</td><td></td><td></td><td></td><td></td></tr><tr><td>December 31, 2007</td><td>129</td><td>71</td><td>29</td><td>229</td></tr><tr><td>December 31, 2008</td><td>121</td><td>57</td><td>21</td><td>199</td></tr><tr><td>December 31, 2009</td><td>122</td><td>49</td><td>23</td><td>194</td></tr><tr><td>December 31, 2010</td><td>119</td><td>43</td><td>21</td><td>183</td></tr><tr><td>Proved Undeveloped Reserves as of:</td><td></td><td></td><td></td><td></td></tr><tr><td>December 31, 2007</td><td>78</td><td>11</td><td>11</td><td>100</td></tr><tr><td>December 31, 2008</td><td>77</td><td>18</td><td>17</td><td>112</td></tr><tr><td>December 31, 2009</td><td>87</td><td>43</td><td>12</td><td>142</td></tr><tr><td>December 31, 2010</td><td>106</td><td>69</td><td>7</td><td>182</td></tr></table>
<table><tr><td></td><td colspan="3">Year Ended December 31,</td></tr><tr><td>(millions)</td><td>2015</td><td>2014</td><td>2013</td></tr><tr><td>Onshore US</td><td>$—</td><td>$42</td><td>$39</td></tr><tr><td>Deepwater Gulf of Mexico</td><td>158</td><td>350</td><td>—</td></tr><tr><td>Equatorial Guinea</td><td>339</td><td>—</td><td>—</td></tr><tr><td>Eastern Mediterranean</td><td>36</td><td>14</td><td>47</td></tr><tr><td>North Sea</td><td>—</td><td>94</td><td>—</td></tr><tr><td>Total</td><td>$533</td><td>$500</td><td>$86</td></tr></table>
<table><tr><td></td><td colspan="3">Year Ended December 31,</td></tr><tr><td>(millions)</td><td>2015</td><td>2014</td><td>2013</td></tr><tr><td>(Gain) Loss on Commodity Derivative Instruments</td><td>$-501</td><td>$-976</td><td>$133</td></tr><tr><td>Interest, Net of Amount Capitalized</td><td>263</td><td>210</td><td>158</td></tr><tr><td>Other Non-Operating (Income) Expense, Net</td><td>-15</td><td>-26</td><td>21</td></tr><tr><td>Total</td><td>$-253</td><td>$-792</td><td>$312</td></tr></table>
<table><tr><td></td><td colspan="3">Year Ended December 31,</td></tr><tr><td>(millions, except per unit)</td><td>2015</td><td>2014</td><td>2013</td></tr><tr><td>Interest Expense</td><td>$407</td><td>$326</td><td>$279</td></tr><tr><td>Capitalized Interest</td><td>-144</td><td>-116</td><td>-121</td></tr><tr><td>Interest Expense, Net</td><td>$263</td><td>$210</td><td>$158</td></tr><tr><td>Unit Rate per BOE<sup>-1</sup></td><td>$2.07</td><td>$1.97</td><td>$1.63</td></tr></table>

Question: what is the percentage change in operating income from 2009 to 2010?
Answer: -0.04756