Table of Contents The following table presents our fixed maturity investment portfolio by ratings of the nationally recognized securities rating organizations as of December 31, 2004:
## Table 0 ##
We are also exposed to the credit risk of our reinsurers.
When we reinsure, we are still liable to our insureds regardless of whether we get reimbursed by our reinsurer.
As part of our overall risk and capacity management strategy, we purchase reinsurance for certain risks underwritten by our various business segments as described above under “— Reinsurance.
” For at least 50% of our $4,133 million of reinsurance recoverables at December 31, 2004, we are protected from the credit risk by using some type of risk mitigation mechanism such as a trust, letter of credit or by withholding the assets in a modified coinsurance or co-fundswithheld arrangement.
For example, reserves of $1,507 million and $882 million as of December 31, 2004 relating to two large coinsurance arrangements with The Hartford and John Hancock, respectively, related to sales of businesses.
If the value of the assets in these trusts falls below the value of the associated liabilities, The Hartford and John Hancock, as the case may be, will be required to put more assets in the trusts.
We may be dependent on the financial condition of The Hartford and John Hancock, whose A. M.  Best ratings are currently A+ and A++, respectively.
For recoverables that are not protected by these mechanisms, we are dependent solely on the credit of the reinsurer.
Occasionally, the credit worthiness of the reinsurer becomes questionable.
See “Item 7 — Management’s Discussion and Analysis of Financial Condition and Results of Operations — Risk Factors — Risks Related to Our Company — Reinsurance may not be available or adequate to protect us against losses, and we are subject to the credit risk of reinsurers.
” We believe that a majority of our reinsurance exposure has been ceded to companies rated “A-“or better by A. M.  Best.
Inflation risk arises as we invest substantial funds in nominal assets, which are not indexed to the level of inflation, whereas the underlying liabilities are indexed to the level of inflation.
Approximately 12% of Assurant PreNeed’s insurance policies with reserves of approximately $398 million as of December 31, 2004 have death benefits that are guaranteed to grow with the CPI.
In times of rapidly rising inflation, the credited death benefit growth on these liabilities increases relative to the investment income earned on the nominal assets resulting in an adverse impact on earnings.
We have partially mitigated this risk by purchasing a contract with payments tied to the CPI.
See “— Derivatives.
” In addition, we have inflation risk in our individual and small employer group health insurance businesses to the extent that medical costs increase with inflation, and we have not been able to increase premiums to keep pace with inflation.
We are exposed to some foreign exchange risk arising from our international operations mainly in Canada.
We also have limited foreign exchange risk exposure to currencies other than the Canadian dollar, primarily the British pound and Danish krone.
Total invested assets denominated in these other currencies were less than 2% of our total invested assets at December 31, 2004.
Foreign exchange risk is mitigated by matching our liabilities under insurance policies that are payable in foreign currencies with investments that are denominated in such currency.
We have not established any hedge to our foreign currency exchange rate exposure.
锘縄nterest Revenue/Expense and Net Interest Margin
## Table 1 ##
In millions of dollars, except as otherwise noted
Note: All interest expense amounts include FDIC deposit insurance assessments.
(1) Net interest revenue includes the taxable equivalent adjustments related to the tax-exempt bond portfolio (based on the U. S.  federal statutory tax rate of 35%) of $462 million, $487 million and $498 million for 2016, 2015 and 2014, respectively.
(2) Excludes expenses associated with certain hybrid financial instruments, which are classified as Long-term debt and accounted for at fair value.
Citi鈥檚 net interest margin (NIM) is calculated by dividing gross interest revenue less gross interest expense by average interest earning assets.
Citi鈥檚 NIM was 2.79% in the fourth quarter of 2016, a decrease of 7 basis points from the third quarter of 2016, driven primarily by lower trading NIM, higher funding costs and the higher mix of promotional rate balances in the U. S.  cards portfolios.
On a full-year basis, Citi鈥檚 NIM declined to 2.86%, compared to 2.93% in 2015, driven primarily by the divestiture of OneMain Financial, the impact of FX translation and lower trading NIM, partially offset by higher loan volumes (including from the Costco portfolio).
As noted in the tables above, Citi鈥檚 interest expense includes the impact of FDIC deposit insurance assessments.
As part of the Dodd-Frank Act, the FDIC is required to ensure that its deposit insurance fund reserve ratio reaches 1.35% by September 30, 2020.
In March 2016, the FDIC issued a final rule that imposes on insured depository institutions with at least $10 billion in assets, which includes Citibank, a surcharge of 4.5 basis points per annum until the fund reaches the required ratio, which the FDIC estimates would take approximately two years.
As previously disclosed, based on its current assessment base, Citi estimates the net impact to Citibank would be approximately $500 million over the two year period beginning in the third quarter of 2016.
PERFORMANCE GRAPH Comparison of Five-Year Cumulative Total Return The following graph and table compare the cumulative total return on Citi’s common stock, which is listed on the NYSE under the ticker symbol “C” and held by 77,787 common stockholders of record as of January 31, 2017, with the cumulative total return of the S&P 500 Index and the S&P Financial Index over the five-year period through December 31, 2016.
The graph and table assume that $100 was invested on December 31, 2011 in Citi’s common stock, the S&P 500 Index and the S&P Financial Index, and that all dividends were reinvested.
Comparison of Five-Year Cumulative Total Return For the years ended
## Table 2 ##

<table><tr><td></td><td></td><td> Percentage of</td></tr><tr><td> Rating</td><td> Fair Value  (In millions)</td><td> Total</td></tr><tr><td>Aaa/Aa/A</td><td>$6,142</td><td>67%</td></tr><tr><td>Baa</td><td>2,493</td><td>27%</td></tr><tr><td>Ba</td><td>416</td><td>5%</td></tr><tr><td>B and lower</td><td>127</td><td>1%</td></tr><tr><td>Total</td><td>$9,178</td><td>100%</td></tr></table>
<table><tr><td>In millions of dollars, except as otherwise noted</td><td>2016</td><td></td><td>2015</td><td></td><td>2014</td><td></td><td>Change2016 vs. 2015</td><td></td><td>Change2015 vs. 2014</td><td></td></tr><tr><td>Interest revenue<sup>-1</sup></td><td>$58,077</td><td></td><td>$59,040</td><td></td><td>$62,180</td><td></td><td>-2%</td><td></td><td>-5%</td><td></td></tr><tr><td>Interest expense</td><td>12,511</td><td></td><td>11,921</td><td></td><td>13,690</td><td></td><td>5</td><td></td><td>-13</td><td></td></tr><tr><td>Net interest revenue<sup>-1(2)</sup></td><td>$45,566</td><td></td><td>$47,119</td><td></td><td>$48,490</td><td></td><td>-3%</td><td></td><td>-3%</td><td></td></tr><tr><td>Interest revenue—average rate</td><td>3.64%</td><td></td><td>3.68%</td><td></td><td>3.72%</td><td></td><td>-4</td><td>bps</td><td>-4</td><td>bps</td></tr><tr><td>Interest expense—average rate</td><td>1.03</td><td></td><td>0.95</td><td></td><td>1.02</td><td></td><td>8</td><td>bps</td><td>-7</td><td>bps</td></tr><tr><td>Net interest margin</td><td>2.86</td><td></td><td>2.93</td><td></td><td>2.90</td><td></td><td>-7</td><td>bps</td><td>3</td><td>bps</td></tr><tr><td>Interest rate benchmarks</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Two-year U.S. Treasury note—average rate</td><td>0.83%</td><td></td><td>0.69%</td><td></td><td>0.46%</td><td></td><td>14</td><td>bps</td><td>23</td><td>bps</td></tr><tr><td>10-year U.S. Treasury note—average rate</td><td>1.83</td><td></td><td>2.14</td><td></td><td>2.54</td><td></td><td>-31</td><td>bps</td><td>-40</td><td>bps</td></tr><tr><td>10-year vs. two-year spread</td><td>100</td><td>bps</td><td>145</td><td>bps</td><td>208</td><td>bps</td><td></td><td></td><td></td><td></td></tr></table>
<table><tr><td>DATE</td><td>CITI</td><td>S&P 500</td><td>S&P FINANCIALS</td></tr><tr><td>31-Dec-2011</td><td>100.0</td><td>100.0</td><td>100.0</td></tr><tr><td>31-Dec-2012</td><td>150.6</td><td>116.0</td><td>128.8</td></tr><tr><td>31-Dec-2013</td><td>198.5</td><td>153.6</td><td>174.7</td></tr><tr><td>31-Dec-2014</td><td>206.3</td><td>174.6</td><td>201.3</td></tr><tr><td>31-Dec-2015</td><td>197.8</td><td>177.0</td><td>198.2</td></tr><tr><td>31-Dec-2016</td><td>229.3</td><td>198.2</td><td>243.4</td></tr></table>

Question: Does Interest expense keeps increasing each year between 2016 and 2015?