## Table 0 ##
(a) Includes crude oil, condensate and natural gas liquids.
The amounts correspond with the basis for fiscal settlements with governments, representing equity tanker liftings and direct deliveries of liquid hydrocarbons.
(b) Our businesses in Ireland and Gabon were sold in 2009.
All periods have been recast to reflect these businesses as discontinued operations.
(c) Includes natural gas acquired for injection and subsequent resale of 22 mmcfd and 32 mmcfd in 2009 and 2008.
(d) Excludes gains and losses on derivative instruments and the unrealized effects of U. K.  natural gas contracts that are accounted for as derivatives.
E&P segment revenues included derivative losses of $13 million in 2009 and gains of $22 million in 2008.
Excluded from E&P segment revenues were gains of $72 million in 2009 and $218 million in 2008 related to natural gas sales contracts in the U. K.  that were accounted for as derivative instruments.
These U. K contracts expired in September 2009.
OSM segment revenues decreased $455 million from 2008 to 2009.
Revenues were impacted by net gains of $12 million in 2009 and $48 million in 2008 on derivative instruments, which expired December 2009.
Excluding the derivatives, the decrease in revenue reflects the almost 40 percent decline in synthetic crude oil realizations.
Synthetic crude oil sales volumes were consistent between the years.
RM&T segment revenues decreased $18,951 million from 2008 to 2009 matching relative price level changes.
While our overall refined product sales volumes in 2009 were relatively unchanged compared to 2008, the level of average petroleum prices declined significantly as shown in Item 1.
Business—Refining, Marketing and Transportation.
The level of crude oil prices has a direct influence on our refined product prices.
The table below shows the average annual refined product benchmark prices for our marketing area.
## Table 1 ##
Sales to related parties decreased in 2009 as a result of the sale of our interest in Pilot Travel Centers LLC (“PTC”) during the fourth quarter of 2008.
Income from equity method investments decreased $467 million in 2009 from 2008 primarily as the result of lower commodity prices on the earnings of many of our equity investees in 2009 and the sale of our equity method investment in PTC during the fourth quarter of 2008.
Net gain on disposal of assets in 2009 includes our gain on the sale of our operated and a portion of our outside-operated Permian Basin producing assets in New Mexico and west Texas, plus sales of other oil and gas properties and retail stores.
In 2008, we sold our outside-operated interests (24 percent of Heimdal field, 47 percent
MARATHON OIL CORPORATIONNotes to Consolidated Financial Statements90Stock-based performance unit awards – During 2018, 2017 and 2016 we granted 754,140, 563,631 and 1,205,517 stockbased performance unit awards to officers.
At December 31, 2018, there were 1,196,176 units outstanding.
Total stock-based performance unit awards expense was $13 million in 2018, $8 million in 2017 and $6 million in 2016.
The key assumptions used in the Monte Carlo simulation to determine the fair value of stock-based performance units granted in 2018, 2017 and 2016 were:
## Table 2 ##
18.
Defined Benefit Postretirement Plans and Defined Contribution PlanWe have noncontributory defined benefit pension plans covering substantially all domestic employees, as well as U. K.  employees who were hired before April 2010.
Certain employees located in E. G. , who are U. S.  or U. K.  based, also participate in these plans.
Benefits under these plans are based on plan provisions specific to each plan.
For the U. K.  pension plan, the principal employer and plan trustees reached a decision to close the plan to future benefit accruals effective December 31, 2015.
We also have defined benefit plans for other postretirement benefits covering our U. S.  employees.
Health care benefits are provided up to age 65 through comprehensive hospital, surgical and major medical benefit provisions subject to various costsharing features.
Post-age 65 health care benefits are provided to certain U. S.  employees on a defined contribution basis.
Life insurance benefits are provided to certain retiree beneficiaries.
These other postretirement benefits are not funded in advance.
Employees hired after 2016 are not eligible for any postretirement health care or life insurance benefits.
MARATHON OIL CORPORATION Notes to Consolidated Financial Statements 92 Components of net periodic benefit cost from continuing operations and other comprehensive (income) loss – The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive (income) loss for our defined benefit pension and other postretirement plans
## Table 3 ##
(a) Settlements are recognized as they occur, once it is probable that lump sum payments from a plan for a given year will exceed the plan’s total service and interest costs for that year.
(b) Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.
The estimated net loss and prior service credit for our defined benefit pension plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2019 are $7 million and $7 million.
The estimated net loss and prior service credit for our other defined benefit postretirement plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2019 are $1 million and $18 million.
Plan assumptions – The following summarizes the assumptions used to determine the benefit obligations at December 31, and net periodic benefit cost for the defined benefit pension and other postretirement plans for 2018, 2017 and 2016.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td>2009</td><td>2008</td></tr><tr><td> E&P Operating Statistics</td><td></td><td></td></tr><tr><td>Average Realizations<sup>(d)</sup></td><td></td><td></td></tr><tr><td>Liquid Hydrocarbons (per bbl)</td><td></td><td></td></tr><tr><td>United States</td><td>$54.67</td><td>$86.68</td></tr><tr><td>Europe</td><td>64.46</td><td>90.60</td></tr><tr><td>Africa</td><td>53.91</td><td>89.85</td></tr><tr><td>Total International</td><td>59.31</td><td>90.14</td></tr><tr><td>Worldwide Continuing Operations</td><td>58.09</td><td>89.07</td></tr><tr><td>Discontinued Operations<sup>(b)</sup></td><td>56.47</td><td>96.41</td></tr><tr><td>Worldwide</td><td>$58.06</td><td>$89.29</td></tr><tr><td>Natural Gas (per mcf)</td><td></td><td></td></tr><tr><td>United States</td><td>$4.14</td><td>$7.01</td></tr><tr><td>Europe</td><td>4.90</td><td>7.67</td></tr><tr><td>Africa</td><td>0.25</td><td>0.25</td></tr><tr><td>Total International</td><td>1.38</td><td>2.50</td></tr><tr><td>Worldwide Continuing Operations</td><td>2.47</td><td>4.56</td></tr><tr><td>Discontinued Operations<sup>(b)</sup></td><td>8.54</td><td>9.62</td></tr><tr><td>Worldwide</td><td>$2.58</td><td>$4.75</td></tr></table>
<table><tr><td><i>(Dollars per gallon)</i></td><td>2009</td><td>2008</td></tr><tr><td>Chicago Spot Unleaded regular gasoline</td><td>$1.68</td><td>$2.50</td></tr><tr><td>Chicago Spot Ultra-low sulfur diesel</td><td>$1.66</td><td>$2.95</td></tr><tr><td>U.S. Gulf Coast Spot Unleaded regular gasoline</td><td>$1.64</td><td>$2.48</td></tr><tr><td>U.S. Gulf Coast Spot Ultra-low sulfur diesel</td><td>$1.66</td><td>$2.93</td></tr></table>
<table><tr><td></td><td>2018</td><td>2017</td><td>2016</td></tr><tr><td>Valuation date stock price</td><td>$14.17</td><td>$14.17</td><td>$14.17</td></tr><tr><td>Expected annual dividend yield</td><td>1.4%</td><td>1.4%</td><td>1.4%</td></tr><tr><td>Expected volatility</td><td>39%</td><td>43%</td><td>52%</td></tr><tr><td>Risk-free interest rate</td><td>2.5%</td><td>2.6%</td><td>2.4%</td></tr><tr><td>Fair value of stock-based performance units outstanding</td><td>$19.60</td><td>$19.45</td><td>$21.51</td></tr></table>
<table><tr><td></td><td colspan="6">Pension Benefits Year Ended December 31,</td><td colspan="3">Other Benefits Year Ended December 31,</td></tr><tr><td></td><td colspan="2">2018</td><td colspan="2">2017</td><td colspan="2">2016</td><td>2018</td><td>2017</td><td>2016</td></tr><tr><td>(In millions)</td><td>U.S.</td><td>Int’l</td><td>U.S.</td><td>Int’l</td><td>U.S.</td><td>Int’l</td><td>U.S.</td><td>U.S.</td><td>U.S.</td></tr><tr><td>Components of net periodic benefit cost:</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Service cost</td><td>$18</td><td>$—</td><td>$22</td><td>$—</td><td>$25</td><td>$—</td><td>$2</td><td>$2</td><td>$2</td></tr><tr><td>Interest cost</td><td>12</td><td>14</td><td>13</td><td>17</td><td>16</td><td>23</td><td>7</td><td>8</td><td>11</td></tr><tr><td>Expected return on plan assets</td><td>-11</td><td>-24</td><td>-13</td><td>-30</td><td>-18</td><td>-35</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Amortization:</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>- prior service cost (credit)</td><td>-10</td><td>—</td><td>-10</td><td>—</td><td>-10</td><td>1</td><td>-8</td><td>-7</td><td>-3</td></tr><tr><td>- actuarial loss</td><td>11</td><td>—</td><td>8</td><td>1</td><td>14</td><td>—</td><td>1</td><td>—</td><td>—</td></tr><tr><td>Net settlement loss<sup>(a)</sup></td><td>18</td><td>3</td><td>28</td><td>4</td><td>97</td><td>6</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Net periodic benefit cost<sup>(b)</sup></td><td>$38</td><td>$-7</td><td>$48</td><td>$-8</td><td>$124</td><td>$-5</td><td>$2</td><td>$3</td><td>$10</td></tr><tr><td>Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Actuarial loss (gain)</td><td>$-4</td><td>$8</td><td>$28</td><td>$-26</td><td>$70</td><td>$41</td><td>$-15</td><td>$5</td><td>$11</td></tr><tr><td>Amortization of actuarial gain (loss)</td><td>-29</td><td>-3</td><td>-36</td><td>-4</td><td>-111</td><td>-6</td><td>-1</td><td>—</td><td>—</td></tr><tr><td>Prior service cost (credit)</td><td>—</td><td>3</td><td>—</td><td>—</td><td>—</td><td>1</td><td>-99</td><td>—</td><td>-38</td></tr><tr><td>Amortization of prior service credit (cost)</td><td>10</td><td>—</td><td>10</td><td>—</td><td>10</td><td>-1</td><td>8</td><td>7</td><td>3</td></tr><tr><td>Total recognized in other comprehensive (income) loss</td><td>$-23</td><td>$8</td><td>$2</td><td>$-30</td><td>$-31</td><td>$35</td><td>$-107</td><td>$12</td><td>$-24</td></tr><tr><td>Total recognized in net periodic benefit cost and other comprehensive (income) loss</td><td>$15</td><td>$1</td><td>$50</td><td>$-38</td><td>$93</td><td>$30</td><td>$-105</td><td>$15</td><td>$-14</td></tr></table>

Question: what was total stock-based performance unit awards expense in 2018 , 2017 , and 2016 , in millions?
Answer: 27
Reasoning program: add(13,const_8), add(#0,const_6)