) increased net cash flows from receivables from improved days sales outstanding offsetting increased sales levels; partially offset by reduced cash flows from increases in inventories to build new product lines and support increased sales levels.
Cash provided by operating activities in 2003 decreased $8.4 million from 2002 due primarily to: ) reduced cash inflows from accounts receivable securitization; and ) reduced cash inflows from increases in inventories partially offset by: ) higher earnings in 2003 before non-cash charges and credits; ) decreased net cash outflows from accounts and other receivables; and ) decreased net cash outflows from accounts payable and accrued expenses.
Net cash used in investing activities in 2004 consisted primarily of the acquisition of PVT and the purchase of ev3’s technology of $137.7 million, and capital expenditures of $42.5 million.
Net cash used in investing activities in 2003 consisted primarily of the acquisition of Jomed, Whitland and Embol-X, Inc.  of $33.2 million, and capital expenditures of $37.9 million.
Net cash used in financing activities in 2004 consisted primarily of purchases of treasury stock of $59.1 million, partially offset by proceeds from stock plans of $30.5 million and net proceeds from issuance of long-term debt of $7.1 million.
Cash used in financing activities in 2003 consisted primarily of purchases of treasury stock of $49.4 million and net payments on debt of $4.0 million, partially offset by proceeds from stock plans of $36.6 million.
A summary of all of the Company’s contractual obligations and commercial commitments as of December 31, 2004 were as follows (in millions):
## Table 0 ##
) increased net cash flows from receivables from improved days sales outstanding offsetting increased sales levels; partially offset by reduced cash flows from increases in inventories to build new product lines and support increased sales levels.
Cash provided by operating activities in 2003 decreased $8.4 million from 2002 due primarily to: ) reduced cash inflows from accounts receivable securitization; and ) reduced cash inflows from increases in inventories partially offset by: ) higher earnings in 2003 before non-cash charges and credits; ) decreased net cash outflows from accounts and other receivables; and ) decreased net cash outflows from accounts payable and accrued expenses.
Net cash used in investing activities in 2004 consisted primarily of the acquisition of PVT and the purchase of ev3’s technology of $137.7 million, and capital expenditures of $42.5 million.
Net cash used in investing activities in 2003 consisted primarily of the acquisition of Jomed, Whitland and Embol-X, Inc.  of $33.2 million, and capital expenditures of $37.9 million.
Net cash used in financing activities in 2004 consisted primarily of purchases of treasury stock of $59.1 million, partially offset by proceeds from stock plans of $30.5 million and net proceeds from issuance of long-term debt of $7.1 million.
Cash used in financing activities in 2003 consisted primarily of purchases of treasury stock of $49.4 million and net payments on debt of $4.0 million, partially offset by proceeds from stock plans of $36.6 million.
A summary of all of the Company’s contractual obligations and commercial commitments as of December 31, 2004 were as follows (in millions):
NORTHROP GRUMMAN CORPORATION -32- AEROSPACE SYSTEMS
## Table 1 ##
2018 – Aerospace Systems sales for 2018 increased $965 million, or 8 percent, as compared with 2017, due to higher volume in each of our three business areas, principally on Manned Aircraft programs.
Manned Aircraft sales were driven by higher restricted and F-35 volume.
Autonomous Systems sales reflect higher volume on several programs, including Triton, partially offset by lower Global Hawk volume.
Space sales reflect higher restricted and Ground Based Strategic Deterrent Technology Maturation Risk Reduction volume, partially offset by lower intercompany and James Webb Space Telescope (JWST) volume.
Operating income for 2018 increased $122 million, or 9 percent, primarily due to higher sales and a higher operating margin rate.
Operating margin rate increased to 10.8 percent from 10.6 percent principally due to improved performance, including the previously noted $69 million of favorable EAC adjustments on multiple restricted programs in 2018, partially offset by the $56 million favorable EAC adjustment recorded in 2017.2017 – Aerospace Systems sales for 2017 increased $1.3 billion, or 12 percent, as compared with 2016, primarily due to higher volume on Manned Aircraft programs.
Manned Aircraft sales were driven by higher restricted sales.
Autonomous Systems sales increased principally due to higher volume for several programs, including Triton, partially offset by lower NATO Alliance Ground Surveillance (AGS) volume.
Space sales increased primarily due to higher restricted sales, partially offset by lower volume on the JWST and Advanced Extremely High Frequency (AEHF) programs.
Operating income for 2017 increased $91 million, or 8 percent, primarily due to higher sales, partially offset by a lower operating margin rate.
Operating margin rate decreased to 10.6 percent from 11.0 percent principally due to changes in contract mix on Manned Aircraft programs and a gain of $45 million recognized in the prior year associated with the sale of a property, partially offset by the previously discussed $56 million favorable EAC adjustment largely related to performance incentives.
INNOVATION SYSTEMS
## Table 2 ##
The sales and operating income above reflect the operating results of Innovation Systems subsequent to the Merger date.
In our comparative discussion below, we reference pro forma sales prepared in accordance with Article 11 of Regulation S-X and computed as if the Merger had been completed as of January 1, 2017.
Refer to Note 2 to the consolidated financial statements for additional supplemental consolidated pro forma financial information.
This pro forma financial information should not be considered indicative of the results that would have actually occurred if the Merger had been consummated on January 1, 2017, nor are they indicative of future results.2018 – Innovation Systems sales for 2018 were $5.6 billion and for 2017 were $4.8 billion, each on a pro forma basis.
The $0.8 billion, or 17 percent, increase reflects higher volume in each business area.
Defense Systems sales reflect increased international volume on armament systems programs and increased volume on the Anti-Radiation Guided Missile program and small caliber ammunition programs.
Flight Systems sales were primarily driven by higher Ground-based Midcourse Defense, A350 and F-35 volume.
Space Systems sales increased primarily due to higher government satellite volume.
NORTHROP GRUMMAN CORPORATION -34- to higher intercompany volume and increased sales on the UKAWACS and Hunter programs, partially offset by lower volume on the KC-10 program as our contract nears completion.
Operating income for 2017 decreased $7 million, or 2 percent, primarily due to lower sales as described above.
Operating margin rate was comparable to the prior year.
PRODUCT AND SERVICE ANALYSIS The following table presents product and service sales and operating costs and expenses by segment:
## Table 3 ##
(1) A reconciliation of segment operating income to total operating income is included in “Segment Operating Results.
” Product Sales and Costs 2018 – Product sales for 2018 increased $4.3 billion, or 25 percent, as compared with 2017.
The increase was primarily due to the addition of $2.9 billion of product sales from Innovation Systems and higher restricted and F-35 volume at Aerospace Systems.
Product costs for 2018 increased $3.8 billion, or 25 percent, as compared with 2017, consistent with the higher product sales described above.2017 – Product sales for 2017 increased $1.5 billion, or 9 percent, as compared with 2016.
The increase was primarily due to higher product sales at Aerospace Systems and Mission Systems.
Higher Aerospace Systems product sales were primarily driven by increased restricted volume, partially offset by lower volume on the JWST and NATO AGS programs.
The increase at Mission Systems was principally due to higher product volume on F-35 sensors, EO/IR self-protection programs and the SABR program.
Product costs for 2017 increased $1.4 billion, or 10 percent, as compared with 2016, consistent with the higher product sales described above and reflects lower product margin rates at Aerospace Systems, principally due to changes in contract mix, and Mission Systems.
Service Sales and Costs 2018 – Service sales for 2018 decreased $238 million, or 2 percent, as compared with 2017.
The decrease was primarily driven by lower service sales at Technology Services principally due to the completion of several programs, partially offset by the addition of $382 million of service sales from Innovation Systems.
NORTHROP GRUMMAN CORPORATION -37- million higher share repurchases and $320 million in payments to credit facilities in 2018, compared with $8.2 billion net proceeds from the issuance of long-term debt in 2017.2017 – Net cash provided by financing activities during 2017 was $7.0 billion compared to net cash used in financing activities of $1.8 billion in 2016.
The change is principally due to $7.5 billion higher net proceeds from the issuance of long-term debt and $1.2 billion lower share repurchases in 2017.
Share Repurchases – See Note 3 to the consolidated financial statements for further information on our share repurchase programs.
Commercial Paper, Credit Facilities and Unsecured Senior Notes – See Note 10 to the consolidated financial statements for further information on our commercial paper, credit facilities and unsecured senior notes.
Financial Arrangements – See Note 12 to the consolidated financial statements for further information on our use of standby letters of credit and guarantees.
Other Sources of Capital – We believe we can obtain additional capital, if necessary for long-term liquidity, from such sources as the public or private capital markets, the sale of assets, sale and leaseback of operating assets, and leasing rather than purchasing new assets.
We have an effective shelf registration statement on file with the SEC, which allows us to access capital in a timely manner.
Contractual Obligations At December 31, 2018, we had contractual commitments to repay debt with interest, make payments under operating leases, settle obligations related to agreements to purchase goods and services and make payments on various other liabilities.
Payments due under these obligations and commitments, and the estimated timing of those payments, are as follows:
## Table 4 ##
(1) A “purchase obligation” is defined as an agreement to purchase goods or services that is enforceable and legally binding on us and that specifies all significant terms, including: fixed or minimum quantities to be purchased; fixed, minimum, or variable price provisions; and the approximate timing of the transaction.
These amounts are primarily comprised of open purchase order commitments to suppliers and subcontractors pertaining to funded contracts.
(2) Other long-term liabilities, including their current portions, primarily consist of total accrued environmental reserves, deferred compensation and other miscellaneous liabilities, of which $159 million is related to environmental reserves recorded in Other current liabilities.
It excludes obligations for uncertain tax positions of $772 million, as the timing of such payments, if any, cannot be reasonably estimated.
The table above excludes estimated minimum funding requirements for the company’s pension and OPB plans, as set forth by the Employee Retirement Income Security Act, as amended.
For further information about future minimum contributions for these plans, see Note 13 to the consolidated financial statements.
Further details regarding long-term debt and operating leases can be found in Notes 10 and 12, respectively, to the consolidated financial statements.
CRITICALACCOUNTING POLICIES, ESTIMATES AND JUDGMENTS Our consolidated financial statements are based on GAAP, which requires us to make estimates and assumptions about future events that affect the amounts reported in our consolidated financial statements.
We employ judgment in making our estimates in consideration of historical experience, currently available information and various other assumptions that we believe to be reasonable under the circumstances.
Actual results could differ from our estimates and assumptions, and any such differences could be material to our consolidated financial statements.
We believe the following accounting policies are critical to the understanding of our consolidated financial statements and require the use of significant management judgment in their application.
For a summary of our significant accounting policies, see Note 1 to the consolidated financial statements.

<table><tr><td></td><td>Payments Due By Period</td></tr><tr><td>Contractual Obligations</td><td>Total</td><td>Less Than 1 Year</td><td>1-3 Years</td><td>4-5 Years</td><td>After 5 Years</td></tr><tr><td>Long-term debt</td><td>$267.1</td><td>$—</td><td>$—</td><td>$—</td><td>$267.1</td></tr><tr><td>Interest on long-term debt</td><td>30.9</td><td>11.2</td><td>15.4</td><td>4.3</td><td>—</td></tr><tr><td>Operating leases</td><td>49.8</td><td>13.1</td><td>20.4</td><td>15.2</td><td>1.1</td></tr><tr><td>Unconditional purchase obligations(a)</td><td>15.1</td><td>7.5</td><td>7.6</td><td>—</td><td>—</td></tr><tr><td>Contractual development obligations(b)</td><td>31.9</td><td>4.3</td><td>3.6</td><td>4.0</td><td>20.0</td></tr><tr><td>Total contractual cash obligations</td><td>$394.8</td><td>$36.1</td><td>$47.0</td><td>$23.5</td><td>$288.2</td></tr></table>
<table><tr><td></td><td colspan="3">Year Ended December 31</td><td colspan="2">% Change in</td></tr><tr><td>$ in millions</td><td>2018</td><td>2017</td><td>2016</td><td>2018</td><td>2017</td></tr><tr><td>Sales</td><td>$13,096</td><td>$12,131</td><td>$10,853</td><td>8%</td><td>12%</td></tr><tr><td>Operating income</td><td>1,411</td><td>1,289</td><td>1,198</td><td>9%</td><td>8%</td></tr><tr><td>Operating margin rate</td><td>10.8%</td><td>10.6%</td><td>11.0%</td><td></td><td></td></tr></table>
<table><tr><td></td><td colspan="3">Year Ended December 31</td><td colspan="2">% Change in</td></tr><tr><td>$ in millions</td><td>2018</td><td>2017</td><td>2016</td><td>2018</td><td>2017</td></tr><tr><td>Sales</td><td>$3,276</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Operating income</td><td>343</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Operating margin rate</td><td>10.5%</td><td>—</td><td>—</td><td></td><td></td></tr></table>
<table><tr><td></td><td colspan="6">Year Ended December 31</td></tr><tr><td>$ in millions</td><td colspan="2">2018</td><td colspan="2">2017</td><td colspan="2">2016</td></tr><tr><td>Segment Information:</td><td>Sales</td><td>Operating Costs and Expenses</td><td>Sales</td><td>Operating Costs and Expenses</td><td>Sales</td><td>Operating Costs and Expenses</td></tr><tr><td>Aerospace Systems</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Product</td><td>$11,087</td><td>$9,889</td><td>$10,064</td><td>$8,988</td><td>$8,947</td><td>$7,945</td></tr><tr><td>Service</td><td>2,009</td><td>1,796</td><td>2,067</td><td>1,854</td><td>1,906</td><td>1,710</td></tr><tr><td>Innovation Systems</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Product</td><td>2,894</td><td>2,582</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Service</td><td>382</td><td>351</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Mission Systems</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Product</td><td>7,329</td><td>6,335</td><td>7,012</td><td>6,088</td><td>6,726</td><td>5,810</td></tr><tr><td>Service</td><td>4,380</td><td>3,854</td><td>4,458</td><td>3,940</td><td>4,435</td><td>3,883</td></tr><tr><td>Technology Services</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Product</td><td>485</td><td>450</td><td>391</td><td>360</td><td>327</td><td>299</td></tr><tr><td>Service</td><td>3,812</td><td>3,404</td><td>4,296</td><td>3,878</td><td>4,438</td><td>4,010</td></tr><tr><td>Segment Totals</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total Product</td><td>$21,795</td><td>$19,256</td><td>$17,467</td><td>$15,436</td><td>$16,000</td><td>$14,054</td></tr><tr><td>Total Service</td><td>10,583</td><td>9,405</td><td>10,821</td><td>9,672</td><td>10,779</td><td>9,603</td></tr><tr><td>Intersegment eliminations</td><td>-2,283</td><td>-2,013</td><td>-2,284</td><td>-2,007</td><td>-2,073</td><td>-1,815</td></tr><tr><td>Total Segment<sup>-1</sup></td><td>$30,095</td><td>$26,648</td><td>$26,004</td><td>$23,101</td><td>$24,706</td><td>$21,842</td></tr></table>
<table><tr><td>$ in millions</td><td>Total</td><td>2019</td><td>2020- 2021</td><td>2022- 2023</td><td>2024 and beyond</td></tr><tr><td>Long-term debt</td><td>$14,475</td><td>$517</td><td>$1,868</td><td>$2,558</td><td>$9,532</td></tr><tr><td>Interest payments on long-term debt</td><td>7,181</td><td>550</td><td>1,008</td><td>903</td><td>4,720</td></tr><tr><td>Operating leases</td><td>2,080</td><td>312</td><td>491</td><td>338</td><td>939</td></tr><tr><td>Purchase obligations<sup>-1</sup></td><td>12,962</td><td>7,167</td><td>3,862</td><td>917</td><td>1,016</td></tr><tr><td>Other long-term liabilities<sup>-2</sup></td><td>1,418</td><td>499</td><td>376</td><td>146</td><td>397</td></tr><tr><td>Total contractual obligations</td><td>$38,116</td><td>$9,045</td><td>$7,605</td><td>$4,862</td><td>$16,604</td></tr></table>

Question: What is the sum of Operating leases in 2019 and Sales in 2018?
Answer: 3588