computers and point-of-care technology carts, as some of our larger customers shifted priorities to reducing costs due to industry consolidation.
Net sales in Other in 2015 increased $327.2 million, or 45.5%, compared 2014.
Other is comprised of CDW Advanced Services, Canada and Kelway.
The increase in net sales was driven by the impact of consolidating five months of Kelway net sales, as well as growth in CDW Advanced Services, partially offset by a decline in the U. S.  dollar-denominated net sales of Canada.
The net sales of Canada in constant currency continued to grow during 2015 compared to 2014.
Gross profit Gross profit increased $194.5 million, or 10.1%, to $2,115.8 million in 2015, compared to $1,921.3 million in 2014.
As a percentage of net sales, Gross profit increased 40 basis points to 16.3% in 2015, from 15.9% in 2014.
Net service contract revenue, including items such as third-party services, warranties and SaaS contributed a positive impact of 15 basis points to gross profit margin as our cost paid to the vendor or third-party service provider is recorded as a reduction to net sales, resulting in net sales being equal to the gross profit on the transaction.
Gross profit margin was positively impacted 15 basis points due to a higher mix of services and improved product margin.
We also experienced a favorable impact of 10 basis points from vendor partner funding.
Vendor partner funding includes purchase discounts, volume rebates and cooperative advertising.
Gross profit margin may fluctuate based on various factors, including vendor incentive and inventory price protection programs, cooperative advertising funds classified as a reduction of cost of sales, product mix, net service contract revenue, commission revenue, pricing strategies, market conditions and other factors.
Selling and administrative expenses Selling and administrative expenses increased $115.7 million, or 10.4%, to $1,226.0 million in 2015, compared to $1,110.3 million in 2014.
As a percentage of total Net sales, Selling and administrative expenses increased 20 basis points to 9.4% in 2015, up from 9.2% in 2014.
Sales payroll costs increased $60.1 million, or 12.0%, year over year, primarily due to increased sales compensation consistent with growth in solutions-related sales, an increase in Gross profit and consolidating five months of incremental Kelway sales payroll costs.
In addition, certain coworker costs increased $9.5 million, or 3.8%, during 2015 compared to the prior year, due to higher costs consistent with increased coworker count, primarily due to our acquisition of Kelway.
Total coworker count was 8,465 at December 31, 2015, up 1,254 from 7,211 at December 31, 2014.
Amortization expense related to intangibles increased $16.7 million, or 9.2%, during 2015 compared to 2014, primarily due to incremental amortization expense related to the intangible assets arising from our acquisition of Kelway.
Non-cash equity-based compensation expense increased $14.8 million, or 90.7%, during 2015 compared to 2014, primarily due to annual equity awards granted under our 2013 LongTerm Incentive Plan in 2015, performance against long-term incentive program targets and equity awards granted in connection with our acquisition of Kelway.
In addition, we incurred $10.2 million of acquisition and integration costs in 2015 related to our acquisition of Kelway.
Income from operations Income from operations by segment, in dollars and as a percentage of Net sales, and the year-over-year percentage change for the years ended December 31, 2015 and 2014 is as follows:
## Table 0 ##
* Not meaningful
(4) The decline in cash flows was driven by the timing of inventory purchases at the end of 2014 versus 2013.
In order to manage our working capital and operating cash needs, we monitor our cash conversion cycle, defined as days of sales outstanding in accounts receivable plus days of supply in inventory minus days of purchases outstanding in accounts payable, based on a rolling three-month average.
Components of our cash conversion cycle are as follows:
## Table 1 ##
(1) Represents the rolling three-month average of the balance of trade accounts receivable, net at the end of the period divided by average daily net sales for the same three-month period.
Also incorporates components of other miscellaneous receivables.
(2) Represents the rolling three-month average of the balance of Merchandise inventory at the end of the period divided by average daily cost of goods sold for the same three-month period.
(3) Represents the rolling three-month average of the combined balance of accounts payable-trade, excluding cash overdrafts, and accounts payable-inventory financing at the end of the period divided by average daily cost of goods sold for the same three-month period.
The cash conversion cycle remained at 21 days at December 31, 2015 and December 31, 2014.
The increase in DSO was primarily driven by a higher Accounts receivable balance at December 31, 2015 driven by higher Public segment sales where customers generally take longer to pay than customers in our Corporate segment, slower government payments in certain states due to budget issues and an increase in Net sales and related Accounts receivable for third-party services such as software assurance and warranties.
These services have an unfavorable impact on DSO as the receivable is recognized on the balance sheet on a gross basis while the corresponding sales amount in the Statement of Operations is recorded on a net basis.
These services have a favorable impact on DPO as the payable is recognized on the balance sheet without a corresponding cost of sale in the Statement of Operations because the cost paid to the vendor or third-party service provider is recorded as a reduction to net sales.
In addition to the impact of these services on DPO, DPO also increased due to the mix of payables with certain vendors that have longer payment terms.
The cash conversion cycle decreased to 21 days at December 31, 2014 compared to 23 days at December 31, 2013, primarily driven by improvement in DSO.
The decline in DSO was primarily driven by improved collections and early payments from certain customers.
Additionally, the timing of inventory receipts at the end of 2014 had a favorable impact on DIO and an unfavorable impact on DPO.
Investing Activities Net cash used in investing activities increased $189.6 million in 2015 compared to 2014.
The increase was primarily due to the completion of the acquisition of Kelway by purchasing the remaining 65% of its outstanding common stock on August 1, 2015.
Additionally, capital expenditures increased $35.1 million to $90.1 million from $55.0 million for 2015 and 2014, respectively, primarily for our new office location and an increase in spending related to improvements to our information technology systems.
Net cash used in investing activities increased $117.7 million in 2014 compared to 2013.
We paid $86.8 million in the fourth quarter of 2014 to acquire a 35% non-controlling interest in Kelway.
Additionally, capital expenditures increased $7.9 million to $55.0 million from $47.1 million in 2014 and 2013, respectively, primarily for improvements to our information technology systems during both years.
Financing Activities Net cash used in financing activities increased $114.5 million in 2015 compared to 2014.
The increase was primarily driven by share repurchases during the year ended December 31, 2015 which resulted in an increase in cash used for financing activities of $241.3 million.
For more information on our share repurchase program, see Item 5, “Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities.
” The increase was partially offset by the changes in accounts payable-inventory financing, which resulted in an increase in cash provided for financing activities of $20.4 million, and the net impact of our debt transactions which resulted in cash outflows of $7.1 million and $145.9 million during the years
high-single digits in local currency in 2016.
Currency was impacted by Canadian dollar to US dollar translation in the first half of the year and British pound to US dollar translation in the second half.
Gross profit Gross profit increased $211 million, or 10.0%, to $2,327 million in 2016, compared to $2,116 million in 2015.
As a percentage of Net sales, Gross profit increased 30 basis points to 16.6% in 2016, from 16.3% in 2015.
Gross profit margin was positively impacted by a higher mix of net service contract revenue as customers looked to extend the life of equipment through warranties, protect their software investments through software assurance and adopt cloud solutions to deliver certain workloads.
All of these solutions grew faster than our overall Net sales.
In addition, vendor partner funding positively impacted gross margin.
These increases helped offset the impact from unfavorable product margin.
Gross profit margin may fluctuate based on various factors, including vendor incentive and inventory price protection programs, cooperative advertising funds classified as a reduction of cost of sales, product mix, net service contract revenue, commission revenue, pricing strategies, market conditions and other factors.
Selling and administrative expenses Selling and administrative expenses increased $119 million, or 9.7%, to $1,345 million in 2016, compared to $1,226 million in 2015.
As a percentage of total Net sales, Selling and administrative expenses increased 20 basis points to 9.6% in 2016, up from 9.4% in 2015.
Payroll costs increased $65 million, or 11.7%, year over year, primarily due to incremental coworker hires at the end of 2015, higher compensation costs consistent with increased Gross profit and the inclusion of twelve months of CDW UK payroll costs in 2016 compared to five months in 2015.
Total coworker count was 8,516 at December 31, 2016, up 51 from 8,465 at December 31, 2015.
Amortization expense related to intangibles increased $18 million, or 8.8%, during 2016 compared to 2015, primarily due to incremental amortization expense related to the intangible assets arising from our acquisition of CDW UK.
Non-cash equity-based compensation expense increased $8 million, or 25.8%, during 2016 compared to 2015, primarily due to annual equity awards granted under our 2013 Long-Term Incentive Plan, performance against long-term incentive program targets and equity awards granted in connection with our acquisition of CDW UK.
Income from operations Income from operations by segment, in dollars and as a percentage of Net sales, and the year-over-year percentage change was as follows:
## Table 2 ##
* Not meaningful (1) Segment income from operations includes the segment’s direct operating income, allocations for certain Headquarters’ costs, allocations for income and expenses from logistics services, certain inventory adjustments and volume rebates and cooperative advertising from vendors.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td colspan="4">Years Ended December 31,</td><td></td></tr><tr><td></td><td colspan="2">2015</td><td colspan="2">2014</td><td></td></tr><tr><td></td><td>Dollars inMillions</td><td>OperatingMargin</td><td>Dollars inMillions</td><td>OperatingMargin</td><td>Percent Changein Incomefrom Operations</td></tr><tr><td>Segments:<sup>-1</sup></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Corporate</td><td>$470.1</td><td>6.9%</td><td>$439.8</td><td>6.8%</td><td>6.9%</td></tr><tr><td>Public</td><td>343.3</td><td>6.7</td><td>313.2</td><td>6.4</td><td>9.6</td></tr><tr><td>Other<sup>-2</sup></td><td>43.1</td><td>4.1</td><td>32.9</td><td>4.6</td><td>31.0</td></tr><tr><td>Headquarters<sup>-3</sup></td><td>-114.5</td><td>nm*</td><td>-112.9</td><td>nm*</td><td>1.4</td></tr><tr><td>Total Income from operations</td><td>$742.0</td><td>5.7%</td><td>$673.0</td><td>5.6%</td><td>10.3%</td></tr></table>
<table><tr><td></td><td>December 31,</td></tr><tr><td>(in days)</td><td>2015</td><td>2014</td><td>2013</td></tr><tr><td>Days of sales outstanding (DSO)<sup>(1)</sup></td><td>48</td><td>42</td><td>44</td></tr><tr><td>Days of supply in inventory (DIO)<sup>(2)</sup></td><td>13</td><td>13</td><td>14</td></tr><tr><td>Days of purchases outstanding (DPO)<sup>(3)</sup></td><td>-40</td><td>-34</td><td>-35</td></tr><tr><td>Cash conversion cycle</td><td>21</td><td>21</td><td>23</td></tr></table>
<table><tr><td></td><td colspan="4">Years Ended December 31,</td><td></td></tr><tr><td></td><td colspan="2">2016</td><td colspan="2">2015</td><td></td></tr><tr><td></td><td>Dollars inMillions</td><td>OperatingMargin</td><td>Dollars inMillions</td><td>OperatingMargin</td><td>Percent Changein Incomefrom Operations</td></tr><tr><td>Segments:<sup>-1</sup></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Corporate<sup>-2(3)(4)</sup></td><td>$453.6</td><td>7.7%</td><td>$432.5</td><td>7.4%</td><td>4.9%</td></tr><tr><td>Small Business<sup>-2(3)(4)</sup></td><td>68.9</td><td>6.0</td><td>68.3</td><td>6.3</td><td>0.9</td></tr><tr><td>Public<sup>-2(4)</sup></td><td>368.0</td><td>6.6</td><td>328.6</td><td>6.3</td><td>12.0</td></tr><tr><td>Other<sup>-4(5)</sup></td><td>43.6</td><td>3.2</td><td>27.1</td><td>3.2</td><td>60.9</td></tr><tr><td>Headquarters<sup>-6</sup></td><td>-114.9</td><td>nm*</td><td>-114.5</td><td>nm*</td><td>0.3</td></tr><tr><td>Total Income from operations</td><td>$819.2</td><td>5.9%</td><td>$742.0</td><td>5.7%</td><td>10.4%</td></tr></table>

Question: Which year is Total Income from operations for section Dollars in Millions the highest?
Answer: 2015