Contractual obligations and commitments Contractual obligations as of December 31, 2014, consisted of the following (in thousands):
## Table 0 ##
(1) Amounts represent principal amounts due and exclude unamortized premiums/discounts reflected on the consolidated balance sheets.
(2) Payment dates include any extension options that we control.
(3) Estimated interest payments on our fixed-rate debt and hedged variable-rate debt were based upon contractual interest rates, including the impact of interest rate swap agreements, interest payment dates, and scheduled maturity dates.
(4) The interest payments on variable-rate debt were based on the interest rates in effect as of December 31, 2014.
Secured notes payable Secured notes payable as of December 31, 2014, consisted of 14 notes secured by 33 properties.
Our secured notes payable typically require monthly payments of principal and interest and had weighted average interest rates of approximately 4.59% as of December 31, 2014.
The total book values of rental properties, land held for future development, and construction in progress securing debt were approximately $1.2 billion as of December 31, 2014.
As of December 31, 2014, our secured notes payable, including unamortized discounts, were composed of approximately $404.0 million and $248.2 million of fixed and variable-rate debt, respectively.
In January 2014, we repaid a $208.7 million secured note payable related to Alexandria Technology Square?
that bore interest at a rate of 5.59%.
Our joint venture partner funded approximately $20.9 million of the proceeds required to repay the secured note payable.
In April 2014, we repaid a $6.4 million secured note payable related to a San Diego property that bore interest at a rate of 4.88%.
In August 2014, we repaid a $7.4 million secured note payable related to a San Diego property that bore interest at a rate of 4.00%.
Estimated interest payments Estimated interest payments on our fixed-rate debt and hedged variable-rate debt were calculated based upon contractual interest rates, including the impact of interest rate swap agreements, interest payment dates, and scheduled maturity dates.
As of December 31, 2014, approximately 84% of our debt was fixed-rate debt or variable-rate debt subject to interest rate swap agreements.
See additional information regarding our interest rate swap agreements under “Liquidity and Capital Resources” – “Contractual Obligations and Commitments” – “Interest Rate Swap Agreements.
” The remaining 16% of our debt as of December 31, 2014, was unhedged variable-rate debt based primarily on LIBOR.
Interest payments on our unhedged variable-rate debt have been calculated based on interest rates in effect as of December 31, 2014.
For additional information regarding our debt, refer to Note 7 – “Secured and Unsecured Senior Debt,” to our consolidated financial statements appearing elsewhere in this annual report on Form 10-K for the year ended December 31, 2014.
Interest rate swap agreements We utilize interest rate swap agreements to hedge a portion of our exposure to variable interest rates primarily associated with our unsecured senior line of credit and unsecured senior bank term loans.
These agreements involve the receipt of variable-rate amounts from a counterparty in exchange for our payment of fixed-rate amounts to the counterparty over the life of the agreement without the exchange of the underlying notional amount.
Interest received under all our interest rate swap agreements is based on the one-month LIBOR.
The net difference between the interest paid and the interest received is reflected as an adjustment to interest expense in our consolidated statements of income.
PART II ITEM 5.
MARKET FOR REGISTRANT’S COMMON EQUITY, RELATED STOCKHOLDER MATTERS, AND ISSUER PURCHASES OF EQUITY SECURITIES Our common stock is traded on the NYSE under the symbol “ARE.
” On January 16, 2018, the last reported sales price per share of our common stock was $124.93, and there were 372 holders of record of our common stock (excluding beneficial owners whose shares are held in the name of Cede & Co. ).
The following table sets forth the quarterly high and low trading prices per share of our common stock as reported on the NYSE and the distributions declared by us with respect to our common stock for each such period (distributions were paid in the quarter following the quarter in which the distribution was declared):
## Table 1 ##
Future distributions on our common stock will be determined by, and at the discretion of, our Board of Directors and will depend on a number of factors, including actual cash available for distribution to our stockholders, our financial condition and capital requirements, the annual distribution requirements under the REIT provisions of the Internal Revenue Code, restrictions under Maryland law, and such other factors as our Board of Directors deems relevant.
To maintain our qualification as a REIT, we must make annual distributions to stockholders of at least 90% of our taxable income for the current taxable year, determined without regard to deductions for dividends paid and excluding any net capital gains.
Under certain circumstances, we may be required to make distributions in excess of cash flow available for distributions to meet these distribution requirements.
In such a case, we may borrow funds or may raise funds through the issuance of additional debt or equity capital.
No dividends can be paid on our common stock unless we have paid full cumulative dividends on our Series D Convertible Preferred Stock.
From the date of issuance of our preferred stock through December 31, 2017 (or April 14, 2017, the date of redemption of all of our 6.45% Series E cumulative redeemable preferred stock (“Series E Redeemable Preferred Stock”)), we have paid full cumulative dividends on our Series D Convertible Preferred Stock and Series E Redeemable Preferred Stock.
We cannot assure our stockholders that we will make any future distributions.
The income tax treatment of distributions on our common stock, Series D Convertible Preferred Stock, and Series E Redeemable Preferred Stock for the years ended December 31, 2017, 2016, and 2015, was as follows:
## Table 2 ##
Refer to “Item 12.
Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters” of this annual report on Form 10-K for information on securities authorized for issuance under equity compensation plans.
the Consolidated Financial Statements (dollars in millions, except per-share amounts) A.
Summary of Significant Accounting Policies Basis of Presentation.
The Consolidated Financial Statements of Arconic Inc.  and subsidiaries (“Arconic” or the “Company”) are prepared in conformity with accounting principles generally accepted in the United States of America (GAAP) and require management to make certain judgments, estimates, and assumptions.
These may affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements.
They also may affect the reported amounts of revenues and expenses during the reporting period.
Actual results could differ from those estimates upon subsequent resolution of identified matters.
Certain prior year amounts have been reclassified to conform to the current year presentation.
The separation of Alcoa Inc.  into two standalone, publicly-traded companies, Arconic Inc.  (the new name for Alcoa Inc. ) and Alcoa Corporation, became effective on November 1, 2016 (the “Separation Transaction”).
The financial results of Alcoa Corporation for all periods prior to the Separation Transaction have been retrospectively reflected in the Statement of Consolidated Operations as discontinued operations and, as such, have been excluded from continuing operations and segment results for all periods presented prior to the Separation Transaction.
The cash flows and comprehensive income related to Alcoa Corporation have not been segregated and are included in the Statement of Consolidated Cash Flows and Statement of Consolidated Comprehensive (Loss) Income, respectively, for all periods presented.
See Note C for additional information related to the Separation Transaction and discontinued operations.
Principles of Consolidation.
The Consolidated Financial Statements include the accounts of Arconic and companies in which Arconic has a controlling interest.
Intercompany transactions have been eliminated.
Investments in affiliates in which Arconic cannot exercise significant influence are accounted for on the cost method.
Management also evaluates whether an Arconic entity or interest is a variable interest entity and whether Arconic is the primary beneficiary.
Consolidation is required if both of these criteria are met.
Arconic does not have any variable interest entities requiring consolidation.
Related Party Transactions.
Arconic buys products from and provides services to Alcoa Corporation following the separation at negotiated prices between the parties.
These transactions were not material to the financial position or results of operations of Arconic for all periods presented.
Effective May 2017, upon disposition of the remaining common stock that Arconic held in Alcoa Corporation, they are no longer deemed a related party.
Cash Equivalents.
Cash equivalents are highly liquid investments purchased with an original maturity of three months or less.
Inventory Valuation.
Inventories are carried at the lower of cost and net realizable value, with cost for approximately half of U. S.  inventories determined under the last-in, first-out (LIFO) method.
The cost of other inventories is determined under a combination of the first-in, first-out (FIFO) and average-cost methods.
Properties, Plants, and Equipment.
Properties, plants, and equipment are recorded at cost.
Depreciation is recorded principally on the straight-line method at rates based on the estimated useful lives of the assets.
The following table details the weighted-average useful lives of structures and machinery and equipment by reporting segment (numbers in years):

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td></td><td colspan="4">Payments by Period</td></tr><tr><td></td><td>Total</td><td>2015</td><td>2016 – 2017</td><td>2018 – 2019</td><td>Thereafter</td></tr><tr><td>Secured and unsecured debt<sup>-1 (2)</sup></td><td>$3,680,940</td><td>$61,190</td><td>$821,528</td><td>$911,468</td><td>$1,886,754</td></tr><tr><td>Estimated interest payments on fixed-rate and hedged variable-rate debt<sup>-3</sup></td><td>705,834</td><td>105,205</td><td>180,103</td><td>159,010</td><td>261,516</td></tr><tr><td>Estimated interest payments on variable-rate debt<sup>-4</sup></td><td>32,061</td><td>8,849</td><td>15,074</td><td>8,138</td><td>—</td></tr><tr><td>Ground lease obligations</td><td>667,082</td><td>9,828</td><td>20,942</td><td>19,573</td><td>616,739</td></tr><tr><td>Other obligations</td><td>8,299</td><td>1,501</td><td>3,051</td><td>3,747</td><td>—</td></tr><tr><td>Total</td><td>$5,094,216</td><td>$186,573</td><td>$1,040,698</td><td>$1,101,936</td><td>$2,765,009</td></tr></table>
<table><tr><td></td><td colspan="4">2017</td><td colspan="4">2016</td></tr><tr><td></td><td>Fourth Quarter</td><td>Third Quarter</td><td>Second Quarter</td><td>First Quarter</td><td>Fourth Quarter</td><td>Third Quarter</td><td>Second Quarter</td><td>First Quarter</td></tr><tr><td>High</td><td>$134.37</td><td>$123.89</td><td>$122.28</td><td>$120.96</td><td>$114.02</td><td>$114.67</td><td>$103.60</td><td>$91.25</td></tr><tr><td>Low</td><td>$118.42</td><td>$116.20</td><td>$109.85</td><td>$106.89</td><td>$101.51</td><td>$100.53</td><td>$89.43</td><td>$70.69</td></tr><tr><td>Per share distribution</td><td>$0.90</td><td>$0.86</td><td>$0.86</td><td>$0.83</td><td>$0.83</td><td>$0.80</td><td>$0.80</td><td>$0.80</td></tr></table>
<table><tr><td></td><td colspan="3">Common Stock</td><td colspan="3">Series D Convertible Preferred Stock</td><td colspan="3">Series E Redeemable Preferred Stock</td></tr><tr><td></td><td colspan="9">Year Ended December 31,</td></tr><tr><td></td><td>2017</td><td>2016</td><td>2015</td><td>2017</td><td>2016</td><td>2015</td><td>2017</td><td>2016</td><td>2015</td></tr><tr><td>Ordinary income</td><td>62.1%</td><td>25.2%</td><td>50.1%</td><td>85.3%</td><td>44.8%</td><td>54.4%</td><td>85.3%</td><td>44.8%</td><td>54.4%</td></tr><tr><td>Return of capital</td><td>27.2</td><td>43.9</td><td>7.9</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Capital gains at 25%</td><td>0.7</td><td>—</td><td>8.5</td><td>1.0</td><td>—</td><td>9.2</td><td>1.0</td><td>—</td><td>9.2</td></tr><tr><td>Capital gains at 20%</td><td>10.0</td><td>30.9</td><td>33.5</td><td>13.7</td><td>55.2</td><td>36.4</td><td>13.7</td><td>55.2</td><td>36.4</td></tr><tr><td>Total</td><td>100.0%</td><td>100.0%</td><td>100.0%</td><td>100.0%</td><td>100.0%</td><td>100.0%</td><td>100.0%</td><td>100.0%</td><td>100.0%</td></tr><tr><td>Dividends declared</td><td>$3.45</td><td>$3.23</td><td>$3.05</td><td>$1.75</td><td>$1.75</td><td>$1.75</td><td>$0.4031</td><td>$1.6125</td><td>$1.6125</td></tr></table>

Question: Which year is Per share distribution the lowest? (in year)
Answer: 2016