given period that have historically been adjudicated as of the reporting period.
For the most recent three months, the incurred claims are estimated primarily from a trend analysis based upon per member per month claims trends developed from our historical experience in the preceding months, adjusted for known changes in estimates of recent hospital and drug utilization data, provider contracting changes, changes in benefit levels, changes in member cost sharing, product mix, and weekday seasonality.
The completion factor method is used for the months of incurred claims prior to the most recent three months because the historical percentage of claims processed for those months is at a level sufficient to produce a consistently reliable result.
Conversely, for the most recent three months of incurred claims, the volume of claims processed historically is not at a level sufficient to produce a reliable result, which therefore requires us to examine historical trend patterns as the primary method of evaluation.
Changes in claim processes, including receipt cycle times, claim inventory levels, recoveries of overpayments, outsourcing, system conversions, and processing disruptions due to weather or other events affect views regarding the reasonable choice of completion factors.
The receipt cycle time measures the average length of time between when a medical claim was initially incurred and when the claim form was received.
Increased electronic claim submissions from providers have decreased the receipt cycle time over the last few years.
For example, the average receipt cycle time has decreased from 15.9 days in 2006 to 15.0 days in 2008 which represents a 6.0% reduction in cycle time over the three year period.
If claims are submitted or processed on a faster (slower) pace than prior periods, the actual claim may be more (less) complete than originally estimated using our completion factors, which may result in reserves that are higher (lower) than required.
Medical cost trends potentially are more volatile than other segments of the economy.
The drivers of medical cost trends include increases in the utilization of hospital facilities, physician services, prescription drugs, and new medical technologies, as well as the inflationary effect on the cost per unit of each of these expense components.
Other external factors such as government-mandated benefits or other regulatory changes, increases in medical services capacity, direct to consumer advertising for prescription drugs and medical services, an aging population, catastrophes, and epidemics also may impact medical cost trends.
Internal factors such as system conversions, claims processing cycle times, changes in medical management practices and changes in provider contracts also may impact our ability to accurately predict estimates of historical completion factors or medical cost trends.
All of these factors are considered in estimating IBNR and in estimating the per member per month claims trend for purposes of determining the reserve for the most recent three months.
Additionally, we continually prepare and review follow-up studies to assess the reasonableness of the estimates generated by our process and methods over time.
The results of these studies are also considered in determining the reserve for the most recent three months.
Each of these factors requires significant judgment by management.
The completion and claims per member per month trend factors are the most significant factors impacting the IBNR estimate.
The portion of IBNR estimated using completion factors for claims incurred prior to the most recent three months is less variable than the portion of IBNR estimated using trend factors.
The following table illustrates the sensitivity of these factors assuming moderate adverse experience and the estimated potential impact on our operating results caused by reasonably likely changes in these factors based on December 31, 2008 data:
## Table 0 ##
Investment Securities Investment securities totaled $8,372.4 million, or 52% of total assets at December 31, 2010, and $7,497.2 million, or 53% of total assets at December 31, 2009.
Debt securities, detailed below, comprised this entire investment portfolio at December 31, 2010 and at December 31, 2009.
The fair value of debt securities were as follows at December 31, 2010 and 2009:
## Table 1 ##
Approximately 96% of our debt securities were investment-grade quality, with an average credit rating of AA by S&P at December 31, 2010.
Most of the debt securities that were below investment-grade were rated BB, the higher end of the below investment-grade rating scale.
Our investment policy limits investments in a single issuer and requires diversification among various asset types.
Tax-exempt municipal securities included pre-refunded bonds of $343.9 million at December 31, 2010 and $346.9 million at December 31, 2009.
These pre-refunded bonds were secured by an escrow fund consisting of U. S.  government obligations sufficient to pay off all amounts outstanding at maturity.
The ratings of these pre-refunded bonds generally assume the rating of the government obligations (AAA by S&P) at the time the fund is established.
In addition, certain monoline insurers guarantee the timely repayment of bond principal and interest when a bond issuer defaults and generally provide credit enhancement for bond issues related to our tax-exempt municipal securities.
We have no direct exposure to these monoline insurers.
We owned $597.2 million and $587.2 million at December 31, 2010 and 2009, respectively, of tax-exempt securities guaranteed by monoline insurers.
The equivalent S&P credit rating of these tax-exempt securities without the guarantee from the monoline insurer was AA.
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 $3.4 million at December 31, 2010 and $5.5 million at December 31, 2009.
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 29.4% at December 31, 2010 and 37.3% at December 31, 2009.
Duration is indicative of the relationship between changes in fair 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 fair values may differ significantly from estimates based on duration.
The average duration of our debt securities was approximately 4.6 years at December 31, 2010.
Including cash equivalents, the average duration was approximately 4.0 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 $395 million.
Humana Inc.  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) 118 15.
STOCKHOLDERS’ EQUITY Dividends The following table provides details of dividend payments, excluding dividend equivalent rights, in 2016, 2017, and 2018 under our Board approved quarterly cash dividend policy:
## Table 2 ##
On November 2, 2018, the Board declared a cash dividend of $0.50 per share that was paid on January 25, 2019 to stockholders of record on December 31, 2018, for an aggregate amount of $68 million.
Declaration and payment of future quarterly dividends is at the discretion of our Board and may be adjusted as business needs or market conditions change.
In February 2019, the Board declared a cash dividend of $0.55 per share payable on April 26, 2019 to stockholders of record on March 29, 2019.
Stock Repurchases Our Board of Directors may authorize the purchase of our common shares.
Under our share repurchase authorization, shares may have been purchased from time to time at prevailing prices in the open market, by block purchases, through plans designed to comply with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended, or in privately-negotiated transactions (including pursuant to accelerated share repurchase agreements with investment banks), subject to certain regulatory restrictions on volume, pricing, and timing.
On February 14, 2017, our Board of Directors authorized the repurchase of up to $2.25 billion of our common shares expiring on December 31, 2017, exclusive of shares repurchased in connection with employee stock plans.
On February 16, 2017, we entered into an accelerated share repurchase agreement, the February 2017 ASR, with Goldman, Sachs & Co.  LLC, or Goldman Sachs, to repurchase $1.5 billion of our common stock as part of the $2.25 billion share repurchase authorized on February 14, 2017.
On February 22, 2017, we made a payment of $1.5 billion to Goldman Sachs from available cash on hand and received an initial delivery of 5.83 million shares of our common stock from Goldman Sachs based on the then current market price of Humana common stock.
The payment to Goldman Sachs was recorded as a reduction to stockholders’ equity, consisting of a $1.2 billion increase in treasury stock, which reflected the value of the initial 5.83 million shares received upon initial settlement, and a $300 million decrease in capital in excess of par value, which reflected the value of stock held back by Goldman Sachs pending final settlement of the February 2017 ASR.
Upon settlement of the February 2017 ASR on August 28, 2017, we received an additional 0.84 million shares as determined by the average daily volume weighted-average share price of our common stock during the term of the agreement of $224.81, less a discount and subject to adjustments pursuant to the terms and conditions of the February 2017 ASR, bringing the total shares received under this program to 6.67 million.
In addition, upon settlement we reclassified the $300 million value of stock initially held back by Goldman Sachs from capital in excess of par value to treasury stock.
Subsequent to settlement of the February 2017 ASR, we repurchased an additional 3.04 million shares in the open market, utilizing the remaining $750 million of the $2.25 billion authorization prior to expiration.
On December 14, 2017, our Board of Directors authorized the repurchase of up to $3.0 billion of our common shares expiring on December 31, 2020, exclusive of shares repurchased in connection with employee stock plans.

Tables referenced above, in order (Table 0 first):
<table><tr><td colspan="2">Completion Factor (a):</td><td colspan="2">Claims Trend Factor (b):</td></tr><tr><td> Factor Change (c)</td><td>Increase (Decrease) in Benefits Payable</td><td>Factor Change (c)</td><td>(Decrease) Increase in Benefits Payable</td></tr><tr><td colspan="4">(dollars in thousands)</td></tr><tr><td>1.50%</td><td>$-183,100</td><td>-7%</td><td>$-300,200</td></tr><tr><td>1.00%</td><td>$-122,100</td><td>-5%</td><td>$-214,400</td></tr><tr><td>0.50%</td><td>$-61,000</td><td>-4%</td><td>$-171,500</td></tr><tr><td>0.25%</td><td>$-30,500</td><td>-3%</td><td>$-128,600</td></tr><tr><td>-0.50%</td><td>$61,000</td><td>-1%</td><td>$-42,900</td></tr><tr><td>-1.00%</td><td>$122,100</td><td>1%</td><td>$42,900</td></tr></table>
<table><tr><td></td><td> December 31, 2010</td><td>Percentage of Total</td><td> December 31, 2009</td><td> Percentage of Total</td></tr><tr><td></td><td colspan="4"> (dollars in thousands)</td></tr><tr><td>U.S. Treasury and other U.S. government corporations and agencies:</td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. Treasury and agency obligations</td><td>$711,613</td><td>8.5%</td><td>$1,009,352</td><td>13.5%</td></tr><tr><td>Mortgage-backed securities</td><td>1,663,179</td><td>19.9%</td><td>1,688,663</td><td>22.5%</td></tr><tr><td>Tax-exempt municipal securities</td><td>2,433,334</td><td>29.1%</td><td>2,224,041</td><td>29.7%</td></tr><tr><td>Mortgage-backed securities:</td><td></td><td></td><td></td><td></td></tr><tr><td>Residential</td><td>55,887</td><td>0.6%</td><td>95,412</td><td>1.3%</td></tr><tr><td>Commercial</td><td>321,031</td><td>3.8%</td><td>279,626</td><td>3.7%</td></tr><tr><td>Asset-backed securities</td><td>149,751</td><td>1.8%</td><td>107,188</td><td>1.4%</td></tr><tr><td>Corporate debt securities</td><td>3,032,311</td><td>36.2%</td><td>2,079,568</td><td>27.7%</td></tr><tr><td>Redeemable preferred stock</td><td>5,333</td><td>0.1%</td><td>13,300</td><td>0.2%</td></tr><tr><td>Total debt securities</td><td>$8,372,439</td><td>100.0%</td><td>$7,497,150</td><td>100.0%</td></tr></table>
<table><tr><td>PaymentDate</td><td>Amountper Share</td><td>TotalAmount (in millions)</td></tr><tr><td>2016</td><td>$1.16</td><td>$172</td></tr><tr><td>2017</td><td>$1.49</td><td>$216</td></tr><tr><td>2018</td><td>$1.90</td><td>$262</td></tr></table>

Question: What is the growing rate of the value of Tax-exempt municipal securities on December 31 in the year where the value of Asset-backed securities on December 31 is higher?
Answer: 0.0941
Reasoning program: subtract(2433334,2224041), divide(#0,2224041)