2015 compared to 2014 When compared to 2014, costs of revenue in 2015 increased $41 million.
This increase included a constant currency increase in expenses of approximately $238 million, or 8.9%, partially offset by a positive impact of approximately $197 million from the effects of foreign currency fluctuations.
The constant currency growth was comprised of a $71 million increase in Commercial Solutions, which included the impact from the Encore acquisition which closed in July 2014, a $146 million increase in Research & Development Solutions, which included the incremental impact from the businesses that Quest contributed to Q2 Solutions, and a $21 million increase in Integrated Engagement Services.
The decrease in costs of revenue as a percent of revenues for 2015 was primarily as a result of an improvement in constant currency profit margin in the Commercial Solutions, Research & Development Solutions and Integrated Engagement Services segments (as more fully described in the segment discussion later in this section).
For 2015, this constant currency profit margin expansion was partially offset by the effect from a higher proportion of consolidated revenues being contributed by our lower margin Integrated Engagement Services segment when compared to 2014 as well as a negative impact from foreign currency fluctuations.
Selling, General and Administrative Expenses, exclusive of Depreciation and Amortization
## Table 0 ##
2016 compared to 2015 The $196 million increase in selling, general and administrative expenses in 2016 included a constant currency increase of $215 million, or 26.4%, partially offset by a positive impact of approximately $19 million from the effects of foreign currency fluctuations.
The constant currency growth was comprised of a $151 million increase in Commercial Solutions, which includes $158 million from the merger with IMS Health, partially offset by a decline in the legacy service offerings, a $32 million increase in Research & Development Solutions, which includes the incremental impact from the businesses that Quest contributed to Q2 Solutions, a $3 million increase in Integrated Engagement Services, and a $29 million increase in general corporate and unallocated expenses, which includes $37 million from the merger with IMS Health.
The constant currency increase in general corporate and unallocated expenses in 2016 was primarily due to higher stock-based compensation expense.2015 compared to 2014 The $34 million increase in selling, general and administrative expenses in 2015 included a constant currency increase of $74 million, or 9.5%, partially offset by a positive impact of approximately $42 million from the effects of foreign currency fluctuations.
The constant currency growth was comprised of a $14 million increase in Commercial Solutions, which included the impact from the Encore acquisition which closed in July 2014, a $40 million increase in Research & Development Solutions, which included the incremental impact from the businesses that Quest contributed to Q2 Solutions, a $4 million increase in Integrated Engagement Services, and a $14 million increase in general corporate and unallocated expenses.
The constant currency increase in general corporate and unallocated expenses in 2015 was primarily due to higher stock-based compensation expense and costs associated with the Q2 Solutions transaction.
Commercial Solutions
## Table 1 ##
Revenues 2016 compared to 2015 Commercial Solutions’ revenues were $1,096 million in 2016, an increase of $773 million over 2015, which includes the incremental impact from the Merger of $806 million.
The constant currency revenue increase was due to the incremental impact from the Merger and from growth in real-world and late phase research services, partially offset by lower revenues from payer provider and advisory services.
The revenue contributed by the Merger in 2016 was negatively impacted by approximately $55 million as a result of adjusting the acquired IMS Health unearned income to fair value as required by purchase accounting.2015 compared to 2014 Commercial Solutions’ revenues were $323 million in 2015, an increase of $93 million, or 40.4%, over 2014.
This increase was comprised of constant currency revenue growth of $98 million, or 42.7%, including $44 million from the Encore acquisition which closed in July 2014, partially offset by a negative impact of approximately $5 million due to the effects of foreign currency fluctuations.
The increase in constant currency revenues was due to the impact from the Encore acquisition which closed in July 2014, as well as growth in real- world and late phase research services, partially offset by lower revenue from advisory services.
Costs of Revenue, exclusive of Depreciation and Amortization 2016 compared to 2015 Commercial Solutions’ costs of revenue increased approximately $405 million in 2016.
This increase was comprised of a $407 million constant currency increase, which includes $438 million from the Merger, offset by lower costs in payer provider and advisory services due to lower revenue volumes, and $2 million due to the negative effects of foreign currency fluctuations.2015 compared to 2014 Commercial Solutions’ costs of revenue increased approximately $65 million in 2015.
This increase was comprised of a $71 million constant currency increase, or 41.1%, partially offset by a reduction of $6 million from the positive effects of foreign currency fluctuations.
The constant currency increase for 2015 was due to the impact of the Encore acquisition and costs to support the growth in real-world and late phase research services
Contract Sales & Medical Solutions
## Table 2 ##
Revenues 2018 compared to 2017 Contract Sales & Medical Solutions’ revenues were $810 million in 2018, a decrease of $105 million, or 11.5%, over 2017.
This decrease was comprised of a constant currency revenue decline of approximately $112 million, or 12.2%, partially offset by a positive impact of approximately $7 million from the effects of foreign currency fluctuations.
The decline in constant currency revenues was largely due to cancellations in 2017 in the Americas region and reduced volume in the Asia-Pacific region.2017 compared to 2016 Contract Sales & Medical Solutions’ revenues were $915 million in 2017, a decrease of $15 million, or 1.6%, over 2016.
This decrease was comprised of a constant currency revenue decline of approximately $10 million, or 1.1%, and a negative impact of approximately $5 million from the effects of foreign currency fluctuations.
The decline in constant currency revenues was due to lower demand in Japan and North America, which was also a result of cancellations that occurred in 2017.
The decline was also due to a $9 million benefit from the acceleration of revenue in the second quarter of 2016 that did not recur in 2017 related to a contract modification on a sales force arrangement that fixed a portion of the contract price that was previously not determinable until future sales-based royalties were known, partially offset by revenue from new projects starting up, primarily in Europe.
Costs of Revenue, exclusive of Depreciation and Amortization 2018 compared to 2017 Contract Sales & Medical Solutions’ costs of revenue, exclusive of depreciation and amortization, decreased $86 million, or 11.2%, in 2018 as compared to 2017.
This decrease included a constant currency decline of approximately $91 million, or 11.8%, partially offset by approximately $5 million from the negative effects of foreign currency fluctuations.
The constant currency cost of revenue decrease was due to a decrease in compensation and related expenses resulting from a decrease in billable headcount.2017 compared to 2016 Contract Sales & Medical Solutions’ costs of revenue, exclusive of depreciation and amortization, decreased $2 million, or 0.3%, in 2017 as compared to 2016.
This decrease included constant currency growth of approximately $2 million, or 0.3%, more than offset by approximately $4 million from the positive effects of foreign currency fluctuations.
The constant currency cost of revenue growth was due to an increase in compensation and related expenses resulting from an increase in billable headcount in Europe as a result of an increase in new projects starting up in the 2017 period.
Selling, General and Administrative Expenses 2018 compared to 2017 Contract Sales & Medical Solutions’ selling, general and administrative expenses decreased $4 million, or 5.5%, in 2018 as compared to 2017, primarily due to lower compensation and related expenses resulting from a reduction in headcount.2017 compared to 2016 Contract Sales & Medical Solutions’ selling, general and administrative expenses decreased $9 million, or 11.0%, in 2017 as compared to 2016, primarily due to lower compensation and related expenses resulting from a decrease in headcount.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td>Year Ended December 31,</td></tr><tr><td>(dollars in millions)</td><td>2016</td><td>2015</td><td>2014</td></tr><tr><td>Selling, general and administrative expenses</td><td>$1,011</td><td>$815</td><td>$781</td></tr><tr><td>% of revenues</td><td>18.8%</td><td>18.8%</td><td>18.8%</td></tr></table>
<table><tr><td></td><td></td><td></td><td></td><td colspan="4"> Change</td></tr><tr><td> (dollars in millions)</td><td> 2016</td><td> 2015</td><td> 2014</td><td colspan="2"> 2016 vs. 2015</td><td colspan="2"> 2015 vs. 2014</td></tr><tr><td>Revenues</td><td>$1,096</td><td>$323</td><td>$230</td><td>$773</td><td>239.3%</td><td>$93</td><td>40.4%</td></tr><tr><td>Costs of revenue</td><td>644</td><td>239</td><td>174</td><td>405</td><td>169.5</td><td>65</td><td>37.4</td></tr><tr><td><i>as a percentage of revenues</i></td><td>58.8%</td><td>74.0%</td><td>75.7%</td><td></td><td></td><td></td><td></td></tr><tr><td>Selling, general and administrative expenses</td><td>216</td><td>65</td><td>52</td><td>151</td><td>232.3</td><td>13</td><td>25.0</td></tr><tr><td><i>as a percentage of revenues</i></td><td>19.7%</td><td>20.1%</td><td>22.6%</td><td></td><td></td><td></td><td></td></tr><tr><td>Segment profit</td><td>$236</td><td>$19</td><td>$4</td><td>$217</td><td>1,142.1%</td><td>$15</td><td>375.0%</td></tr><tr><td><i>as a percentage of revenues</i></td><td>21.5%</td><td>5.9%</td><td>1.7%</td><td></td><td></td><td></td><td></td></tr></table>
<table><tr><td></td><td colspan="3">Year Ended December 31,</td><td colspan="4">Change</td></tr><tr><td>(dollars in millions)</td><td>2018</td><td>2017</td><td>2016</td><td colspan="2">2018 vs. 2017</td><td colspan="2">2017 vs. 2016</td></tr><tr><td>Revenues</td><td>$810</td><td>$915</td><td>$930</td><td>$-105</td><td>-11.5%</td><td>$-15</td><td>-1.6%</td></tr><tr><td>Costs of revenue, exclusive of depreciationand amortization</td><td>682</td><td>768</td><td>770</td><td>-86</td><td>-11.2</td><td>-2</td><td>-0.3</td></tr><tr><td>Selling, general and administrative expenses</td><td>69</td><td>73</td><td>82</td><td>-4</td><td>-5.5</td><td>-9</td><td>-11.0</td></tr><tr><td>Segment profit</td><td>$59</td><td>$74</td><td>$78</td><td>$-15</td><td>-20.3%</td><td>$-4</td><td>-5.1%</td></tr></table>

Question: Which year is Selling, general and administrative expenses the most?
Answer: 2016