Table of Contents Rent expense under all operating leases, including both cancelable and noncancelable leases, was $645 million, $488 million and $338 million in 2013, 2012 and 2011, respectively.
Future minimum lease payments under noncancelable operating leases having remaining terms in excess of one year as of September 28, 2013, are as follows (in millions):
## Table 0 ##
Other Commitments As of September 28, 2013, the Company had outstanding off-balance sheet third-party manufacturing commitments and component purchase commitments of $18.6 billion.
In addition to the off-balance sheet commitments mentioned above, the Company had outstanding obligations of $1.3 billion as of September 28, 2013, which consisted mainly of commitments to acquire capital assets, including product tooling and manufacturing process equipment, and commitments related to advertising, research and development, Internet and telecommunications services and other obligations.
Contingencies The Company is subject to various legal proceedings and claims that have arisen in the ordinary course of business and that have not been fully adjudicated.
In the opinion of management, there was not at least a reasonable possibility the Company may have incurred a material loss, or a material loss in excess of a recorded accrual, with respect to loss contingencies.
However, the outcome of litigation is inherently uncertain.
Therefore, although management considers the likelihood of such an outcome to be remote, if one or more of these legal matters were resolved against the Company in a reporting period for amounts in excess of management’s expectations, the Company’s consolidated financial statements for that reporting period could be materially adversely affected.
Apple Inc.  v.  Samsung Electronics Co. , Ltd, et al.
On August 24, 2012, a jury returned a verdict awarding the Company $1.05 billion in its lawsuit against Samsung Electronics Co. , Ltd and affiliated parties in the United States District Court, Northern District of California, San Jose Division.
On March 1, 2013, the District Court upheld $599 million of the jury’s award and ordered a new trial as to the remainder.
Because the award is subject to entry of final judgment, partial re-trial and appeal, the Company has not recognized the award in its results of operations.
VirnetX, Inc.  v.  Apple Inc.  et al.
On August 11, 2010, VirnetX, Inc.  filed an action against the Company alleging that certain of its products infringed on four patents relating to network communications technology.
On November 6, 2012, a jury returned a verdict against the Company, and awarded damages of $368 million.
The Company is challenging the verdict, believes it has valid defenses and has not recorded a loss accrual at this time.
CF INDUSTRIES HOLDINGS, INC.  5 The following table summarizes our nitrogen fertilizer production volume for the last three years
## Table 1 ##
(1) Gross ammonia production, including amounts subsequently upgraded on-site into granular urea, UAN or AN.
Donaldsonville, Louisiana The Donaldsonville nitrogen fertilizer complex is the world's largest nitrogen fertilizer production facility.
It has six ammonia plants, five urea plants, four nitric acid plants, three UAN plants, and one DEF plant.
The complex, which is located on the Mississippi River, includes deep-water docking facilities, access to an ammonia pipeline, and truck and railroad loading capabilities.
The complex has on-site storage for 160,000 tons of ammonia, 201,000 tons of UAN (measured on a 32% nitrogen content basis) and 173,000 tons of granular urea.
As part of our capacity expansion projects, the new Donaldsonville urea plant became operational during the fourth quarter of 2015.
The new UAN plant was placed in service in the first quarter of 2016, and the new ammonia plant was placed in service in October 2016.
For additional details regarding the capacity expansion projects, see Item 7.
Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources.
Medicine Hat, Alberta, Canada Medicine Hat is the largest nitrogen fertilizer complex in Canada.
It has two ammonia plants and one urea plant.
The complex has on-site storage for 60,000 tons of ammonia and 60,000 tons of granular urea.
Port Neal, Iowa The Port Neal facility is located approximately 12 miles south of Sioux City, Iowa on the Missouri River.
The facility consists of two ammonia plants, three urea plants, two nitric acid plants and a UAN plant.
The location has on-site storage for 90,000 tons of ammonia, 154,000 tons of granular urea, and 81,000 tons of 32% UAN.
As part of our capacity expansion projects, both the ammonia and urea plants were placed in service in December 2016.
For additional details regarding the capacity expansion projects, see Item 7.
Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources.
Verdigris, Oklahoma The Verdigris facility is located northeast of Tulsa, Oklahoma, near the Verdigris River and is owned by TNLP.
It is the second largest UAN production facility in North America.
The facility comprises two ammonia plants, two nitric acid plants, two UAN plants and a port terminal.
Through our approximately 75.3% interest in TNCLP and its subsidiary, TNLP, we operate the plants and lease the port terminal from the Tulsa-Rogers County Port Authority.
The complex has on-site storage for 60,000 tons of ammonia and 100,000 tons of 32% UAN.
Woodward, Oklahoma The Woodward facility is located in rural northwest Oklahoma and consists of an ammonia plant, two nitric acid plants, two urea plants and two UAN plants.
The facility has on-site storage for 36,000 tons of ammonia and 84,000 tons of 32% UAN.
Yazoo City, Mississippi The Yazoo City facility is located in central Mississippi and includes one ammonia plant, four nitric acid plants, an AN plant, two urea plants, a UAN plant and a dinitrogen tetroxide production and storage facility.
The site has on-site storage for 50,000 tons of ammonia, 48,000 tons of 32% UAN and 11,000 tons of AN and related products.
Cost of Sales.
Cost of sales per ton in our ammonia segment averaged $248 per ton in 2016, including the impact of the CF Fertilisers UK acquisition, which averaged $220 per ton.
The remaining cost of sales per ton was $250 in 2016, a 16% decrease from the $296 per ton in 2015.
The decrease was due primarily to the impact of unrealized net mark-to-market gains on natural gas derivatives in 2016 compared to losses in 2015 and to the impact of lower realized natural gas costs in 2016.
This was partly offset by capacity expansion project start-up costs of $50 million and an increase in expansion project depreciation as a result of the new ammonia plants at our Donaldsonville and Port Neal facilities.
Granular Urea Segment Our granular urea segment produces granular urea, which contains 46% nitrogen.
Produced from ammonia and carbon dioxide, it has the highest nitrogen content of any of our solid nitrogen fertilizers.
Granular urea is produced at our Courtright, Ontario; Donaldsonville, Louisiana; Medicine Hat, Alberta; and Port Neal, Iowa nitrogen complexes.
The following table presents summary operating data for our granular urea segment:
## Table 2 ##
N/M—Not Meaningful (1) Granular urea represents 46% nitrogen content.
Nutrient tons represent the tons of nitrogen within the product tons.
Year Ended December 31, 2017 Compared to Year Ended December 31, 2016 Net Sales.
Net sales in the granular urea segment increased by $140 million, or 17%, to $971 million in 2017 compared to $831 million in 2016 due primarily to a 21% increase in sales volume partially offset by a 3% decrease in average selling prices.
Sales volume was higher due primarily to increased production at our new Port Neal facility, which came on line in the fourth quarter of 2016.
Average selling prices decreased to $223 per ton in 2017 compared to $231 per ton in 2016 due primarily to greater global nitrogen supply availability due to global capacity additions.
Selling prices strengthened in the fourth quarter of 2017 rising approximately 14% compared to the prior year period.
Cost of Sales.
Cost of sales per ton in our granular urea segment averaged $197 in 2017, a 22% increase from the $162 per ton in 2016.
The increase was due primarily to higher depreciation as a result of the new granular urea plant at our Port Neal facility, an unrealized net mark-to-market loss on natural gas derivatives in 2017 compared to a gain in the comparable period of 2016 and higher realized natural gas costs, including the impact of realized derivatives.
These increases in cost of sales were partially offset by the impact of production efficiencies due to increased volume.
Depreciation and amortization in our granular urea segment in 2017 was $56 per ton compared to $31 per ton in 2016.

Tables referenced above, in order (Table 0 first):
<table><tr><td>2014</td><td>$610</td></tr><tr><td>2015</td><td>613</td></tr><tr><td>2016</td><td>587</td></tr><tr><td>2017</td><td>551</td></tr><tr><td>2018</td><td>505</td></tr><tr><td>Thereafter</td><td>1,855</td></tr><tr><td>Total minimum lease payments</td><td>$4,721</td></tr></table>
<table><tr><td></td><td colspan="3">December 31,</td></tr><tr><td></td><td>2017</td><td>2016</td><td>2015</td></tr><tr><td></td><td colspan="3">(tons in thousands)</td></tr><tr><td>Ammonia<sup>-1</sup></td><td>10,295</td><td>8,307</td><td>7,673</td></tr><tr><td>Granular urea</td><td>4,451</td><td>3,368</td><td>2,520</td></tr><tr><td>UAN -32%</td><td>6,914</td><td>6,698</td><td>5,888</td></tr><tr><td>AN</td><td>2,127</td><td>1,845</td><td>1,283</td></tr></table>
<table><tr><td></td><td colspan="7">Year ended December 31,</td></tr><tr><td></td><td>2017</td><td>2016</td><td>2015</td><td colspan="2">2017 v. 2016</td><td colspan="2">2016 v. 2015</td></tr><tr><td></td><td colspan="7">(in millions, except as noted)</td></tr><tr><td>Net sales</td><td>$971</td><td>$831</td><td>$788</td><td>$140</td><td>17%</td><td>$43</td><td>5%</td></tr><tr><td>Cost of sales</td><td>856</td><td>584</td><td>469</td><td>272</td><td>47%</td><td>115</td><td>25%</td></tr><tr><td>Gross margin</td><td>$115</td><td>$247</td><td>$319</td><td>$-132</td><td>-53%</td><td>$-72</td><td>-23%</td></tr><tr><td>Gross margin percentage</td><td>11.8%</td><td>29.7%</td><td>40.4%</td><td>-17.9%</td><td></td><td>-10.7%</td><td></td></tr><tr><td>Sales volume by product tons (000s)</td><td>4,357</td><td>3,597</td><td>2,460</td><td>760</td><td>21%</td><td>1,137</td><td>46%</td></tr><tr><td>Sales volume by nutrient tons (000s)<sup>(1)</sup></td><td>2,004</td><td>1,654</td><td>1,132</td><td>350</td><td>21%</td><td>522</td><td>46%</td></tr><tr><td>Average selling price per product ton</td><td>$223</td><td>$231</td><td>$320</td><td>$-8</td><td>-3%</td><td>$-89</td><td>-28%</td></tr><tr><td>Average selling price per nutrient ton<sup>-1</sup></td><td>$485</td><td>$502</td><td>$696</td><td>$-17</td><td>-3%</td><td>$-194</td><td>-28%</td></tr><tr><td>Gross margin per product ton</td><td>$26</td><td>$69</td><td>$129</td><td>$-43</td><td>-62%</td><td>$-60</td><td>-47%</td></tr><tr><td>Gross margin per nutrient ton<sup>-1</sup></td><td>$57</td><td>$149</td><td>$281</td><td>$-92</td><td>-62%</td><td>$-132</td><td>-47%</td></tr><tr><td>Depreciation and amortization</td><td>$246</td><td>$112</td><td>$51</td><td>$134</td><td>120%</td><td>$61</td><td>120%</td></tr><tr><td>Unrealized net mark-to-market loss (gain) on natural gas derivatives</td><td>$16</td><td>$-67</td><td>$47</td><td>$83</td><td>N/M</td><td>$-114</td><td>N/M</td></tr></table>

Question: In which year is Sales volume by product tons (000s) positive?
Answer: 2017