licensed software upgrade rights, installation fees, transaction processing and subscriptions, decreased 1% from 2016 to 2015.
The decrease in system sales was primarily driven by a decline in technology resale.  ?
Support and maintenance revenues increased 4% to $1.0 billion in 2016 compared to $976 million in 2015.
This increase was primarily attributable to continued success selling Cerner Millennium applications and implementing them at client sites.  ?
Services revenue, which includes professional services (excluding installation) and managed services, increased 16% to $2.4 billion in 2016 from $2.1 billion in 2015.
This increase was driven by a $207 million increase in professional services due to growth in implementation and consulting activities and growth in managed services of $124 million as a result of continued demand for our hosting services.
Revenue backlog, which reflects contracted revenue that has not yet been recognized as revenue, increased 12% to $15.9 billion in 2016 compared to $14.2 billion in 2015.
This increase was driven by solid levels of new business bookings revenue during the past four quarters, including strong levels of managed services bookings that typically have longer contract terms.
Costs of Revenue Costs of revenue as a percent of total revenues were 16% in 2016 compared to 17% in 2015.
The lower costs of revenue as a percent of total revenues was primarily driven by a lower mix of technology resale, which carries a higher cost of revenue.
Costs of revenue includes the cost of reimbursed travel expense, sales commissions, third party consulting services and subscription content and computer hardware, devices and sublicensed software purchased from manufacturers for delivery to clients.
It also includes the cost of hardware maintenance and sublicensed software support subcontracted to the manufacturers.
Such costs, as a percent of total revenues, typically have varied as the mix of revenue (software, hardware, devices, maintenance, support, services and reimbursed travel) carrying different margin rates changes from period to period.
Costs of revenue does not include the costs of our client service personnel who are responsible for delivering our service offerings.
Such costs are included in sales and client service expense.
Operating Expenses Total operating expenses increased 7% to $3.1 billion in 2016, compared with $2.9 billion in 2015.  ?
Sales and client service expenses as a percent of total revenues were 43% in 2016, compared to 42% in 2015.
These expenses increased 13% to $2.1 billion in 2016, from $1.8 billion in 2015.
Sales and client service expenses include salaries and benefits of sales, marketing, support, and services personnel, depreciation and other expenses associated with our managed services business, communications expenses, unreimbursed travel expenses, expense for share-based payments, and trade show and advertising costs.
The growth in services expense and increase as a percent of total revenues reflects hiring of services personnel to support the strong growth in services revenue.  ?
Software development expenses as a percent of total revenues were 11% in 2016, compared to 12% in 2015.
Expenditures for software development include ongoing development and enhancement of the Cerner Millennium and HealtheIntent platforms, with a focus on supporting key initiatives to enhance physician experience, revenue cycle and population health solutions.
A summary of our total software development expense in 2016 and 2015 is as follows:
## Table 0 ##
?
General and administrative expenses as a percent of total revenues were 8% in 2016, compared to 10% in 2015.
These expenses decreased 7% to $392 million in 2016, from $423 million in 2015.
General and administrative expenses include salaries and benefits for corporate, financial and administrative staffs, utilities, communications
Fiscal Year 2015 Compared to Fiscal Year 2014
## Table 1 ##
Revenues & Backlog Revenues increased 30% to $4.4 billion in 2015, as compared to $3.4 billion in 2014.  ?
System sales increased 36% to $1.3 billion in 2015 from $946 million in 2014.
The increase in system sales was primarily driven by contributions from the Cerner Health Services business.  ?
Support and maintenance revenues increased 35% to $976 million in 2015 compared to $725 million in 2014.
This increase was primarily attributable to contributions from the Cerner Health Services business.  ?
Services revenue increased 28% to $2.1 billion in 2015 from $1.6 billion in 2014.
This increase was driven by contributions from the Cerner Health Services business.
Revenue backlog increased 34% to $14.2 billion in 2015 compared to $10.6 billion in 2014.
This increase was driven by growth in new business bookings during the past four quarters, including continued strong levels of managed services, Cerner ITWorks and Cerner revenue cycle services bookings that typically have longer contract terms, coupled with contributions from the Cerner Health Services business.
Costs of Revenue Costs of revenue as a percent of total revenues were 17% in 2015 compared to 18% in 2014.
The lower costs of revenue as a percent of total revenues was primarily driven by a lower mix of technology resale, which carries a higher cost of revenue.
Operating Expenses Total operating expenses increased 42% to $2.9 billion in 2015, compared with $2.0 billion in 2014.
Equity Compensation Plan Information The following table presents the equity securities available for issuance under our equity compensation plans as of December 31, 2012.
## Table 2 ##
(1) Includes grants made under the Huntington Ingalls Industries, Inc.  2012 Long-Term Incentive Stock Plan (the "2012 Plan"), which was approved by our stockholders on May 2, 2012, and the Huntington Ingalls Industries, Inc.  2011 Long-Term Incentive Stock Plan (the "2011 Plan"), which was approved by the sole stockholder of HII prior to its spin-off from Northrop Grumman Corporation.
Of these shares, 1,166,492 were subject to stock options, 2,060,138 were subject to outstanding restricted performance stock rights, 641,556 were restricted stock rights, and 63,033 were stock rights granted under the 2011 Plan.
In addition, this number includes 9,129 stock rights and 5,763 restricted performance stock rights granted under the 2012 Plan, assuming target performance achievement.
(2) This is the weighted average exercise price of the 1,166,492 outstanding stock options only.
(3) There are no awards made under plans not approved by security holders.
ITEM 13.
CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE Information as to certain relationships and related transactions and director independence will be incorporated herein by reference to the Proxy Statement for our 2013 Annual Meeting of Stockholders to be filed within 120 days after the end of the Company’s fiscal year.
ITEM 14.
PRINCIPAL ACCOUNTANT FEES AND SERVICES Information as to principal accountant fees and services will be incorporated herein by reference to the Proxy Statement for our 2013 Annual Meeting of Stockholders to be filed within 120 days after the end of the Company’s fiscal year.

<table><tr><td></td><td colspan="2">For the Years Ended</td></tr><tr><td>(In thousands)</td><td>2016</td><td>2015</td></tr><tr><td>Software development costs</td><td>$704,882</td><td>$685,260</td></tr><tr><td>Capitalized software costs</td><td>-290,911</td><td>-262,177</td></tr><tr><td>Capitalized costs related to share-based payments</td><td>-2,785</td><td>-2,479</td></tr><tr><td>Amortization of capitalized software costs</td><td>140,232</td><td>119,195</td></tr><tr><td>Total software development expense</td><td>$551,418</td><td>$539,799</td></tr></table>
<table><tr><td>(In thousands)</td><td>2015</td><td>% ofRevenue</td><td>2014</td><td>% ofRevenue</td><td>% Change</td></tr><tr><td>Revenues</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>System sales</td><td>$1,281,890</td><td>29%</td><td>$945,858</td><td>28%</td><td>36%</td></tr><tr><td>Support and maintenance</td><td>975,701</td><td>22%</td><td>724,840</td><td>21%</td><td>35%</td></tr><tr><td>Services</td><td>2,094,874</td><td>47%</td><td>1,642,119</td><td>48%</td><td>28%</td></tr><tr><td>Reimbursed travel</td><td>72,802</td><td>2%</td><td>89,886</td><td>3%</td><td>-19%</td></tr><tr><td>Total revenues</td><td>4,425,267</td><td>100%</td><td>3,402,703</td><td>100%</td><td>30%</td></tr><tr><td>Costs of revenue</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Costs of revenue</td><td>750,781</td><td>17%</td><td>604,377</td><td>18%</td><td>24%</td></tr><tr><td>Total margin</td><td>3,674,486</td><td>83%</td><td>2,798,326</td><td>82%</td><td>31%</td></tr><tr><td>Operating expenses</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Sales and client service</td><td>1,838,600</td><td>42%</td><td>1,395,568</td><td>41%</td><td>32%</td></tr><tr><td>Software development</td><td>539,799</td><td>12%</td><td>392,805</td><td>12%</td><td>37%</td></tr><tr><td>General and administrative</td><td>423,424</td><td>10%</td><td>233,393</td><td>7%</td><td>81%</td></tr><tr><td>Amortization of acquisition-related intangibles</td><td>91,527</td><td>2%</td><td>13,476</td><td>—%</td><td>579%</td></tr><tr><td>Total operating expenses</td><td>2,893,350</td><td>65%</td><td>2,035,242</td><td>60%</td><td>42%</td></tr><tr><td>Total costs and expenses</td><td>3,644,131</td><td>82%</td><td>2,639,619</td><td>78%</td><td>38%</td></tr><tr><td>Operating earnings</td><td>781,136</td><td>18%</td><td>763,084</td><td>22%</td><td>2%</td></tr><tr><td>Other income, net</td><td>244</td><td></td><td>11,090</td><td></td><td></td></tr><tr><td>Income taxes</td><td>-242,018</td><td></td><td>-248,741</td><td></td><td></td></tr><tr><td>Net earnings</td><td>$539,362</td><td></td><td>$525,433</td><td></td><td>3%</td></tr></table>
<table><tr><td>Plan category</td><td>Number of Securities to be Issued Upon Exercise of Outstanding Options, Warrants and Rights<sup>-1</sup> (a)(b)</td><td>Weighted-Average Exercise Price of Outstanding Options,Warrants and Rights<sup>-2</sup></td><td>Number of Securities Remaining Available for Future Issuance Under Equity Compensation Plans (Excluding SecuritiesReflected in Column (a)) (c)</td></tr><tr><td>Equity compensation plans approved by security holders</td><td>3,946,111</td><td>$34.67</td><td>3,608,527</td></tr><tr><td>Equity compensation plans not approved by security holders<sup>-3</sup></td><td>—</td><td>—</td><td>—</td></tr><tr><td>Total</td><td>3,946,111</td><td>$34.67</td><td>3,608,527</td></tr></table>

Question: What is the sum of Software development costs of For the Years Ended 2016, Software development Operating expenses of 2015, and Software development Operating expenses of 2014 ?
Answer: 1637486