Humana Inc.  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) value, or the excess of the market value over the exercise or purchase price, of stock options exercised and restricted stock awards vested during the period.
The actual tax benefit realized for the deductions taken on our tax returns from option exercises and restricted stock vesting totaled $16.3 million in 2009, $16.9 million in 2008, and $48.0 million in 2007.
There was no capitalized stock-based compensation expense.
The stock plans provide that one restricted share is equivalent to 1.7 stock options.
At December 31, 2009, there were 12,818,855 shares reserved for stock award plans, including 4,797,304 shares of common stock available for future grants assuming all stock options or 2,821,944 shares available for future grants assuming all restricted shares.
Stock Options Stock options are granted with an exercise price equal to the average market value of the underlying common stock on the date of grant.
Our stock plans, as approved by the Board of Directors and stockholders, define average market value as the average of the highest and lowest stock prices reported by the New York Stock Exchange on a given date.
Exercise provisions vary, but most options vest in whole or in part 1 to 3 years after grant and expire 7 to 10 years after grant.
Upon grant, stock options are assigned a fair value based on the Black-Scholes valuation model.
Compensation expense is recognized on a straight-line basis over the total requisite service period, generally the total vesting period, for the entire award.
For stock options granted on or after January 1, 2010 to retirement eligible employees, the compensation expense is recognized on a straight-line basis over the shorter of the requisite service period or the period from the date of grant to an employee’s eligible retirement date.
The weighted-average fair value of each option granted during 2009, 2008, and 2007 is provided below.
The fair value was estimated on the date of grant using the Black-Scholes pricing model with the weighted-average assumptions indicated below:
## Table 0 ##
When valuing employee stock options, we stratify the employee population into three homogenous groups that historically have exhibited similar exercise behaviors.
These groups are executive officers, directors, and all other employees.
We value the stock options based on the unique assumptions for each of these employee groups.
We calculate the expected term for our employee stock options based on historical employee exercise behavior and base the risk-free interest rate on a traded zero-coupon U. S.  Treasury bond with a term substantially equal to the option’s expected term.
The volatility used to value employee stock options is based on historical volatility.
We calculate historical volatility using a simple-average calculation methodology based on daily price intervals as measured over the expected term of the option.
As required under the current contract, the target underwritten health care cost and underwriting fee amounts for each option period are negotiated.
Any variance from the target health care cost is shared with the federal government.
Accordingly, events and circumstances not contemplated in the negotiated target health care cost amount may have a material adverse effect on us.
These changes may include an increase or reduction in the number of persons enrolled or eligible to enroll due to the federal government’s decision to increase or decrease U. S.  military deployments.
In the event government reimbursements were to decline from projected amounts, our failure to reduce the health care costs associated with these programs may have a material adverse effect on our results of operations, financial position, and cash flows.
In July 2009, we were notified by the Department of Defense that we were not awarded the third generation TRICARE program contract for the South Region which had been subject to competing bids.
We filed a protest with the GAO in connection with the award to another contractor citing discrepancies between the award criteria and procedures prescribed in the request for proposals issued by the DoD and those that appear to have been used by the DoD in making its contractor selection.
In October 2009, we learned that the GAO had upheld our protest, determining that the TMA evaluation of our proposal had unreasonably failed to fully recognize and reasonably account for the likely cost savings associated with our record of obtaining network provider discounts from our established network in the South Region.
On December 22, 2009, we were advised that TMA notified the GAO of its intent to implement corrective action consistent with the discussion contained within the GAO’s decision with respect to our protest.
At this time, we are not able to determine what actions TMA will take in response to recommendations by the GAO, nor can we determine whether or not the protest decision by the GAO will have any effect upon the ultimate disposition of the contract award.
Critical Accounting Policies and Estimates The discussion and analysis of our financial condition and results of operations is based upon our consolidated financial statements and accompanying notes, which have been prepared in accordance with accounting principles generally accepted in the United States of America.
The preparation of these financial statements and accompanying notes requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes.
We continuously evaluate our estimates and those critical accounting policies related primarily to benefit expenses and revenue recognition as well as accounting for impairments related to our investment securities, goodwill, and long-lived assets.
These estimates are based on knowledge of current events and anticipated future events and, accordingly, actual results ultimately may differ from those estimates.
We believe the following critical accounting policies involve the most significant judgments and estimates used in the preparation of our consolidated financial statements.
Benefit Expense Recognition Benefit expenses are recognized in the period in which services are provided and include an estimate of the cost of services which have been incurred but not yet reported, or IBNR.
IBNR represents a substantial portion of our benefits payable as follows:
## Table 1 ##
Our direct exposure to subprime mortgage lending is limited to investment in residential mortgage-backed securities and asset-backed securities backed by home equity loans.
The fair value of securities backed by Alt-A and subprime loans was $5.5 million at December 31, 2009 and $7.6 million at December 31, 2008.
There are no collateralized debt obligations or structured investment vehicles in our investment portfolio.
The percentage of corporate securities associated with the financial services industry was 37.3% at December 31, 2009 and 41.7% at December 31, 2008.
Duration is indicative of the relationship between changes in market value and changes in interest rates, providing a general indication of the sensitivity of the fair values of our debt securities to changes in interest rates.
However, actual market values may differ significantly from estimates based on duration.
The average duration of our debt securities was approximately 4.5 years at December 31, 2009.
Including cash equivalents, the average duration was approximately 3.8 years.
Based on the duration including cash equivalents, a 1% increase in interest rates would generally decrease the fair value of our securities by approximately $340 million.
Gross unrealized losses and fair values aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position were as follows at December 31, 2009 and 2008, respectively:
## Table 2 ##
In April 2009, the Financial Accounting Standards Board, or the FASB, issued new guidance to address concerns about (1) measuring the fair value of financial instruments when the markets become inactive and quoted prices may reflect distressed transactions and (2) recording impairment charges on investments in debt securities.
The new guidance highlights and expands on the factors that should be considered in estimating fair value when the volume and level of activity for a financial asset or liability has significantly decreased and requires new disclosures relating to fair value measurement inputs and valuation techniques (including changes in inputs and valuation techniques).
In addition, new guidance regarding recognition and presentation of otherthan-temporary impairments changed (1) the trigger for determining whether an other-than-temporary impairment exists and (2) the amount of an impairment charge to be recorded in earnings.
We adopted the provisions of the new guidance for the quarter ended June 30, 2009.
Refer to Note 4 and Note 5 to the consolidated financial statements included in Item 8.
—Financial Statements and Supplementary Data for disclosures related to the implementation of the new guidance.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td>2009</td><td>2008</td><td>2007</td></tr><tr><td>Weighted-average fair value at grant date</td><td>$14.24</td><td>$17.95</td><td>$21.07</td></tr><tr><td>Expected option life (years)</td><td>4.6</td><td>5.1</td><td>4.8</td></tr><tr><td>Expected volatility</td><td>39.2%</td><td>28.2%</td><td>28.9%</td></tr><tr><td>Risk-free interest rate at grant date</td><td>1.9%</td><td>2.9%</td><td>4.5%</td></tr><tr><td>Dividend yield</td><td>None</td><td>None</td><td>None</td></tr></table>
<table><tr><td></td><td> December 31, 2009</td><td>Percentage of Total</td><td> December 31, 2008</td><td> Percentage of Total</td></tr><tr><td></td><td colspan="4"> (dollars in thousands)</td></tr><tr><td>IBNR</td><td>$1,902,700</td><td>59.0%</td><td>$1,851,047</td><td>57.7%</td></tr><tr><td>Reported claims in process</td><td>357,718</td><td>11.1%</td><td>486,514</td><td>15.2%</td></tr><tr><td>Other benefits payable</td><td>682,961</td><td>21.2%</td><td>561,221</td><td>17.5%</td></tr><tr><td>Benefits payable, excluding military services</td><td>2,943,379</td><td>91.3%</td><td>2,898,782</td><td>90.4%</td></tr><tr><td>Military services benefits payable</td><td>279,195</td><td>8.7%</td><td>306,797</td><td>9.6%</td></tr><tr><td>Total benefits payable</td><td>$3,222,574</td><td>100.0%</td><td>$3,205,579</td><td>100.0%</td></tr></table>
<table><tr><td></td><td colspan="2">Less than 12 months</td><td colspan="2">12 months or more</td><td colspan="2">Total</td></tr><tr><td></td><td> Fair Value</td><td>Gross Unrealized Losses</td><td> Fair Value</td><td>Gross Unrealized Losses</td><td> Fair Value</td><td>Gross Unrealized Losses</td></tr><tr><td></td><td colspan="6">(in thousands)</td></tr><tr><td> December 31, 2009</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. Treasury and other U.S. government corporations and agencies:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. Treasury and agency obligations</td><td>$301,843</td><td>$-2,425</td><td>$2,970</td><td>$-109</td><td>$304,813</td><td>$-2,534</td></tr><tr><td>Mortgage-backed securities</td><td>823,365</td><td>-11,005</td><td>6,834</td><td>-323</td><td>830,199</td><td>-11,328</td></tr><tr><td>Tax-exempt municipal securities</td><td>598,520</td><td>-14,286</td><td>198,327</td><td>-9,131</td><td>796,847</td><td>-23,417</td></tr><tr><td>Mortgage-backed securities:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Residential</td><td>1,771</td><td>-5</td><td>73,178</td><td>-10,994</td><td>74,949</td><td>-10,999</td></tr><tr><td>Commercial</td><td>31,941</td><td>-359</td><td>142,944</td><td>-8,281</td><td>174,885</td><td>-8,640</td></tr><tr><td>Asset-backed securities</td><td>1,930</td><td>-19</td><td>2,179</td><td>-88</td><td>4,109</td><td>-107</td></tr><tr><td>Corporate debt securities</td><td>636,833</td><td>-9,354</td><td>99,830</td><td>-11,972</td><td>736,663</td><td>-21,326</td></tr><tr><td>Total debt securities</td><td>$2,396,203</td><td>$-37,453</td><td>$526,262</td><td>$-40,898</td><td>$2,922,465</td><td>$-78,351</td></tr></table>

Question: what was the percent of the change of the expected volatility from 2008 to 2009
Answer: 0.39007
Reasoning program: subtract(39.2,28.2), divide(#0,28.2)