Ending membership was as follows at December 31, 2010 and 2009:
## Table 0 ##
(a) The Commercial segment provides a full range of insured specialty products including dental, vision, and other supplemental products.
Members included in these products may not be unique to each product since members have the ability to enroll in multiple products.
These tables of financial data should be reviewed in connection with the discussion that follows.
Summary Net income was $1,099.4 million, or $6.47 per diluted common share, in 2010 compared to $1,039.7 million, or $6.15 per diluted common share, in 2009.
The increase primarily was due to improved operating performance in the Government segment as a result of an increase in average Medicare Advantage membership and prior year favorable reserve releases not in the ordinary course of business in 2010 in both our Government and Commercial segments.
These increases were partially offset by a $147.5 million ($0.55 per diluted common share) write-down of deferred acquisition costs associated with our individual major medical policies and a net charge of $138.9 million ($0.52 per diluted common share) for reserve strengthening associated with our closed block of long-term care policies in our Commercial Segment in 2010 as discussed in Note 18 to the consolidated financial statements included in Item 8.
– Financial Statements and Supplementary Data.
Excluding these items, Commercial segment pretax earnings improved year over year due to decreased utilization, our continued focus on pricing discipline and administrative cost reductions, as well as the previously mentioned prior year favorable reserve releases.
The prior year favorable reserve development in both our Government and Commercial segments (approximately $0.86 per diluted common share in 2010) primarily resulted from improvements in the claims processing environment and, to a lesser extent, better than originally estimated utilization as well as a shortening of the cycle time associated with provider claim submissions.
Net income for 2009 also included the favorable impact of the reduction of the liability for unrecognized tax benefits ($0.10 per diluted common share) as a result of Internal Revenue Service audit settlements.
Regulatory Requirements Certain of our subsidiaries operate in states that regulate the payment of dividends, loans, or other cash transfers to Humana Inc. , our parent company, and require minimum levels of equity as well as limit investments to approved securities.
The amount of dividends that may be paid to Humana Inc.  by these subsidiaries, without prior approval by state regulatory authorities, is limited based on the entity’s level of statutory income and statutory capital and surplus.
In most states, prior notification is provided before paying a dividend even if approval is not required.
Although minimum required levels of equity are largely based on premium volume, product mix, and the quality of assets held, minimum requirements can vary significantly at the state level.
Our state regulated subsidiaries had aggregate statutory capital and surplus of approximately $4.3 billion and $3.8 billion as of December 31, 2010 and 2009, respectively, which exceeded aggregate minimum regulatory requirements.
The amount of dividends that may be paid to our parent company in 2011 without prior approval by state regulatory authorities is approximately $740 million in the aggregate.
This compares to dividends that were able to be paid in 2010 without prior regulatory approval of approximately $720 million.
Contractual Obligations We are contractually obligated to make payments for years subsequent to December 31, 2010 as follows:
## Table 1 ##
(1) Interest includes the estimated contractual interest payments under our debt agreements.
(2) We lease facilities, computer hardware, and other equipment under long-term operating leases that are noncancelable and expire on various dates through 2025.
We sublease facilities or partial facilities to third party tenants for space not used in our operations which partially mitigates our operating lease commitments.
An operating lease is a type of off-balance sheet arrangement.
Assuming we acquired the asset, rather than leased such asset, we would have recognized a liability for the financing of these assets.
See also Note 16 to the consolidated financial statements included in Item 8.
—Financial Statements and Supplementary Data.
(3) Purchase obligations include agreements to purchase services, primarily information technology related services, or to make improvements to real estate, in each case that are enforceable and legally binding on us and that specify all significant terms, including: fixed or minimum levels of service to be purchased; fixed, minimum or variable price provisions; and the appropriate timing of the transaction.
Purchase obligations exclude agreements that are cancelable without penalty.
(4) Includes future policy benefits payable ceded to third parties through 100% coinsurance agreements as more fully described in Note 19 to the consolidated financial statements included in Item 8.
—Financial Statements and Supplementary Data.
We expect the assuming reinsurance carriers to fund these obligations and reflected these amounts as reinsurance recoverables included in other long-term assets on our consolidated balance sheet.
Amounts payable in less than one year are included in trade accounts payable and accrued expenses in the consolidated balance sheet.
Humana Inc.  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) 108 Amortization expense for other intangible assets was approximately $75 million in 2017, $77 million in 2016, and $93 million in 2015.
The following table presents our estimate of amortization expense for each of the five next succeeding fiscal years:
## Table 2 ##

<table><tr><td></td><td colspan="2"></td><td colspan="2">Change</td></tr><tr><td></td><td> 2010</td><td> 2009</td><td>Members</td><td>Percentage</td></tr><tr><td> Medical Membership:</td><td></td><td></td><td></td><td></td></tr><tr><td>Government segment:</td><td></td><td></td><td></td><td></td></tr><tr><td>Medicare Advantage</td><td>1,733,800</td><td>1,508,500</td><td>225,300</td><td>14.9%</td></tr><tr><td>Medicare Advantage ASO</td><td>28,200</td><td>0</td><td>28,200</td><td>100.0%</td></tr><tr><td>Total Medicare Advantage</td><td>1,762,000</td><td>1,508,500</td><td>253,500</td><td>16.8%</td></tr><tr><td>Medicare stand-alone PDP</td><td>1,758,800</td><td>1,927,900</td><td>-169,100</td><td>-8.8%</td></tr><tr><td>Total Medicare</td><td>3,520,800</td><td>3,436,400</td><td>84,400</td><td>2.5%</td></tr><tr><td>Military services</td><td>1,755,200</td><td>1,756,000</td><td>-800</td><td>0.0%</td></tr><tr><td>Military services ASO</td><td>1,272,600</td><td>1,278,400</td><td>-5,800</td><td>-0.5%</td></tr><tr><td>Total military services</td><td>3,027,800</td><td>3,034,400</td><td>-6,600</td><td>-0.2%</td></tr><tr><td>Medicaid</td><td>572,400</td><td>401,700</td><td>170,700</td><td>42.5%</td></tr><tr><td>Total Government</td><td>7,121,000</td><td>6,872,500</td><td>248,500</td><td>3.6%</td></tr><tr><td>Commercial segment:</td><td></td><td></td><td></td><td></td></tr><tr><td>Fully-insured</td><td>1,663,400</td><td>1,839,500</td><td>-176,100</td><td>-9.6%</td></tr><tr><td>ASO</td><td>1,453,600</td><td>1,571,300</td><td>-117,700</td><td>-7.5%</td></tr><tr><td>Total Commercial</td><td>3,117,000</td><td>3,410,800</td><td>-293,800</td><td>-8.6%</td></tr><tr><td>Total medical membership</td><td>10,238,000</td><td>10,283,300</td><td>-45,300</td><td>-0.4%</td></tr><tr><td> Specialty Membership:</td><td></td><td></td><td></td><td></td></tr><tr><td>Commercial segment (a)</td><td>7,076,100</td><td>7,109,900</td><td>-33,800</td><td>-0.5%</td></tr></table>
<table><tr><td></td><td colspan="5"> Payments Due by Period</td></tr><tr><td></td><td> Total</td><td> Less than 1 Year</td><td> 1-3 Years</td><td> 3-5 Years</td><td> More than 5 Years</td></tr><tr><td></td><td colspan="5"> (in thousands)</td></tr><tr><td>Debt</td><td>$1,586,988</td><td>$447</td><td>$333</td><td>$125</td><td>$1,586,083</td></tr><tr><td>Interest -1</td><td>1,203,133</td><td>114,226</td><td>225,342</td><td>217,507</td><td>646,058</td></tr><tr><td>Operating leases -2</td><td>810,234</td><td>190,525</td><td>295,868</td><td>190,164</td><td>133,677</td></tr><tr><td>Purchase obligations -3</td><td>148,169</td><td>81,376</td><td>63,050</td><td>3,743</td><td>0</td></tr><tr><td>Future policy benefits payable and other long-term liabilities -4</td><td>1,818,658</td><td>52,936</td><td>249,311</td><td>138,078</td><td>1,378,333</td></tr><tr><td>Total</td><td>$5,567,182</td><td>$439,510</td><td>$833,904</td><td>$549,617</td><td>$3,744,151</td></tr></table>
<table><tr><td></td><td>(in millions)</td></tr><tr><td>For the years ending December 31,</td><td></td></tr><tr><td>2018</td><td>$64</td></tr><tr><td>2019</td><td>54</td></tr><tr><td>2020</td><td>52</td></tr><tr><td>2021</td><td>19</td></tr><tr><td>2022</td><td>16</td></tr></table>

Question: what was the average amortization expense between 2015 and 2017