M & T BANK CORPORATION AND SUBSIDIARIES Notes to Financial Statements — (Continued)A summary of investment securities that as of December 31, 2006 and 2005 had been in a continuous unrealized loss position for less than twelve months and those that had been in a continuous unrealized loss position for twelve months or longer follows:
## Table 0 ##
The Company owned approximately five hundred individual investment securities with aggregate gross unrealized losses of $88,985,000 at December 31, 2006.
Those investment securities consisted predominantly of mortgage-backed securities classified as available for sale.
The unrealized losses at December 31, 2006 were generally attributable to the level of interest rates and, accordingly, were considered to be temporary in nature.
At December 31, 2006, the Company had not identified events or changes in circumstance which may have a significant adverse effect on the fair value of the $356,851,000 of cost method investment securities.
At December 31, 2006, investment securities with a carrying value of $4,422,316,000, including $4,158,346,000 of investment securities available for sale, were pledged to secure demand notes issued to the U. S.  Treasury, borrowings from various Federal Home Loan Banks (“FHLB”), repurchase agreements, governmental deposits and interest rate swap agreements.
Investment securities pledged by the Company to secure obligations whereby the secured party is permitted by contract or custom to sell or repledge such collateral totaled $1,300,322,000 at December 31, 2006.
The pledged securities are included in mortgage-backed securities available for sale.
At December 31, 2006, collateral accepted by the Company which by contract or custom can be sold or repledged consisted of securities with a fair value of $104,205,000 purchased under agreements to resell.
Those securities have been pledged at December 31, 2006 to secure governmental deposits.
M & T BANK CORPORATION AND SUBSIDIARIES Notes to Financial Statements — (Continued) the exposure to changes in the fair value of certain commitments to originate real estate loans for sale.
As a result of these activities, net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale, and commitments to sell loans were approximately $4 million at December 31, 2006, compared with unrealized pre-tax losses of $5 million at December 31, 2005.
Changes in unrealized gains or losses are included in mortgage banking revenues and, in general, are realized in subsequent periods as the related loans are sold and commitments satisfied.
Derivative financial instruments used for trading purposes included interest rate contracts, foreign exchange and other option contracts, foreign exchange forward and spot contracts, and financial futures.
Interest rate contracts entered into for trading purposes had notional values and estimated fair value gains of $7.6 billion and $17,122,000, respectively, at December 31, 2006 and notional values and estimated fair value gains of $6.7 billion and $12,486,000, respectively, at December 31, 2005.
Foreign exchange and other option and futures contracts totaled approximately $613 million and $679 million at December 31, 2006 and 2005, respectively.
Such contracts were valued at gains of $477,000 and $428,000 at December 31, 2006 and 2005, respectively.
Trading account assets and liabilities are recorded in the consolidated balance sheet at estimated fair value.
The following table includes information about the estimated fair value of derivative financial instruments used for trading purposes:
## Table 1 ##
Net gains realized from derivative financial instruments used for trading purposes were $14,800,000, $14,380,000 and $11,144,000 in 2006, 2005 and 2004, respectively.18.
Variable interest entities and asset securitizations Variable interest entities Variable interest entities in which the Company holds a significant variable interest are described below.
M&T Auto Receivables I, LLC is a special purpose subsidiary of M&T Bank formed in 2002 for the purpose of borrowing $500 million in a revolving asset-backed structured borrowing with an unaffiliated conduit lender.
The revolving asset-backed structured borrowing is secured by automobile loans and other assets transferred to the special purpose subsidiary by M&T Bank or other of its subsidiaries that totaled $565 million and $572 million at December 31, 2006 and 2005, respectively.
The activities of M&T Auto Receivables I, LLC are generally restricted to purchasing and owning automobile loans for the purpose of securing this revolving borrowing arrangement.
Proceeds from payments on the automobile loans are required to be applied in priority order for fees, principal and interest on the borrowing, and funding the monthly replenishment of loans.
Any remaining proceeds are available for distribution to M&T Bank.
The secured borrowing is prepayable, in whole or in part, at any time and is non-recourse to M&T Bank and the Company.
However, 80% of the borrowing can be put back to M&T Bank upon demand.
The Company’s maximum incremental exposure to loss resulting from the structure of this borrowing arrangement is generally restricted to the amount that such borrowing is overcollateralized.
Management currently estimates no material losses as a result of the pledging of assets and the terms of the borrowing arrangement.
The assets and liabilities of M&T Auto Receivables I, LLC have been included in the Company’s consolidated financial statements.
M&T has a variable interest in a trust that holds American Depositary Shares of AIB (“AIB ADSs”) for the purpose of satisfying options to purchase such shares for certain employees.
The trust purchased the AIB ADSs with the proceeds of a loan from an entity subsequently acquired by M&T.
Proceeds from option exercises and any dividends and other earnings on the trust assets are used to repay the loan plus
M & T BANK CORPORATION AND SUBSIDIARIES Notes to Financial Statements — (Continued) services which are secured by various types of multifamily residential and commercial real estate and deposit services to its customers.
Activities of this segment include the origination, sales and servicing of commercial real estate loans.
The Discretionary Portfolio segment includes securities, residential mortgage loans and other assets; short-term and long-term borrowed funds; brokered certificates of deposit and interest rate swap agreements related thereto; and offshore branch deposits.
This segment also provides foreign exchange services to customers.
The Residential Mortgage Banking segment originates and services residential mortgage loans for consumers and sells substantially all of those loans in the secondary market to investors or to bank subsidiaries of M&T.
The segment periodically purchases servicing rights to loans that have been originated by other entities.
This segment also originates and services loans to developers of residential real estate properties.
Residential mortgage loans held for sale are included in the Residential Mortgage Banking segment.
The Retail Banking segment offers a variety of services to consumers and small businesses through several delivery channels that include banking offices, automated teller machines, telephone banking and Internet banking.
The “All Other” category includes other operating activities of the Company that are not directly attributable to the reported segments as determined in accordance with SFAS No.131, the difference between the provision for credit losses and the calculated provision allocated to the reportable segments, goodwill and core deposit and other intangible assets resulting from acquisitions of financial institutions, the net impact of the Company’s internal funds transfer pricing methodology, eliminations of transactions between reportable segments, certain nonrecurring transactions, the residual effects of unallocated support systems and general and administrative expenses, and the impact of interest rate risk management strategies.
The amount of intersegment activity eliminated in arriving at consolidated totals was included in the “All Other” category as follows:
## Table 2 ##
The Company conducts substantially all of its operations in the United States.
There are no transactions with a single customer that in the aggregate result in revenues that exceed ten percent of consolidated total revenues.22.
Regulatory matters Payment of dividends by M&T’s banking subsidiaries is restricted by various legal and regulatory limitations.
Dividends from any banking subsidiary to M&T are limited by the amount of earnings of the banking subsidiary in the current year and the preceding two years.
For purposes of this test, at December 31, 2006, approximately $108,084,000 was available for payment of dividends to M&T from banking subsidiaries without prior regulatory approval.
Banking regulations prohibit extensions of credit by the subsidiary banks to M&T unless appropriately secured by assets.
Securities of affiliates are not eligible as collateral for this purpose.
The bank subsidiaries are required to maintain noninterest-earning reserves against certain deposit liabilities.
During the maintenance periods that included December 31, 2006 and 2005, cash and due from banks included a daily average of $182,953,000 and $388,697,000, respectively, for such purpose.
Federal regulators have adopted capital adequacy guidelines for bank holding companies and banks.
Failure to meet minimum capital requirements can result in certain mandatory, and possibly additional discretionary, actions by regulators that, if undertaken, could have a material effect on the Company’s financial statements.
Under the capital adequacy guidelines, the so-called “Tier 1 capital” and “Total capital” as a percentage of risk-weighted assets and certain off-balance sheet financial instruments must be at least 4% and 8%, respectively.
In addition to these risk-based measures, regulators also require banking institutions that meet certain qualitative criteria to maintain a minimum “leverage” ratio of “Tier 1 capital” to average total assets, adjusted for goodwill and certain other items, of at least 3% to be
Operating Expenses
## Table 3 ##
Operating expenses increased $348 million in 2012 versus 2011.
Depreciation, wage and benefit inflation, higher fuel prices and volumerelated trucking services purchased by our logistics subsidiaries, contributed to higher expenses during the year.
Efficiency gains, volume related fuel savings (2% fewer gallons of fuel consumed) and $38 million of weather related expenses in 2011, which favorably affects the comparison, partially offset the cost increase.
Operating expenses increased $1.8 billion in 2011 versus 2010.
Our fuel price per gallon rose 36% during 2011, accounting for $922 million of the increase.
Wage and benefit inflation, volume-related costs, depreciation, and property taxes also contributed to higher expenses.
Expenses increased $20 million for costs related to the flooding in the Midwest and $18 million due to the impact of severe heat and drought in the South, primarily Texas.
Cost savings from productivity improvements and better resource utilization partially offset these increases.
A $45 million one-time payment relating to a transaction with CSX Intermodal, Inc (CSXI) increased operating expenses during the first quarter of 2010, which favorably affects the comparison of operating expenses in 2011 to those in 2010.
Compensation and Benefits – Compensation and benefits include wages, payroll taxes, health and welfare costs, pension costs, other postretirement benefits, and incentive costs.
Expenses in 2012 were essentially flat versus 2011 as operational improvements and cost reductions offset general wage and benefit inflation and higher pension and other postretirement benefits.
In addition, weather related costs increased these expenses in 2011.
A combination of general wage and benefit inflation, volume-related expenses, higher training costs associated with new hires, additional crew costs due to speed restrictions caused by the Midwest flooding and heat and drought in the South, and higher pension expense drove the increase during 2011 compared to 2010.
Fuel – Fuel includes locomotive fuel and gasoline for highway and non-highway vehicles and heavy equipment.
Higher locomotive diesel fuel prices, which averaged $3.22 per gallon (including taxes and transportation costs) in 2012, compared to $3.12 in 2011, increased expenses by $105 million.
Volume, as measured by gross ton-miles, decreased 2% in 2012 versus 2011, driving expense down.
The fuel consumption rate was flat year-over-year.
Higher locomotive diesel fuel prices, which averaged $3.12 (including taxes and transportation costs) in 2011, compared to $2.29 per gallon in 2010, increased expenses by $922 million.
In addition, higher gasoline prices for highway and non-highway vehicles also increased year-over-year.
Volume, as measured by gross ton-miles, increased 5% in 2011 versus 2010, driving expense up by $122 million.
Purchased Services and Materials – Expense for purchased services and materials includes the costs of services purchased from outside contractors and other service providers (including equipment

<table><tr><td></td><td colspan="2">Less Than 12 Months</td><td colspan="2">12 Months or More</td></tr><tr><td></td><td> Fair Value</td><td>Unrealized Losses</td><td> Fair Value</td><td>Unrealized Losses</td></tr><tr><td></td><td colspan="4">(In thousands)</td></tr><tr><td>December 31, 2006</td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. Treasury and federal agencies</td><td>$207,522</td><td>$-397</td><td>$266,354</td><td>$-5,382</td></tr><tr><td>Obligations of states and political subdivisions</td><td>5,348</td><td>-2</td><td>1,462</td><td>-13</td></tr><tr><td>Mortgage-backed securities:</td><td></td><td></td><td></td><td></td></tr><tr><td>Government issued or guaranteed</td><td>68,832</td><td>-112</td><td>1,467,818</td><td>-40,064</td></tr><tr><td>Privately issued</td><td>564,993</td><td>-3,754</td><td>2,413,828</td><td>-38,284</td></tr><tr><td>Other debt securities</td><td>3,425</td><td>-77</td><td>53,353</td><td>-473</td></tr><tr><td>Equity securities</td><td>29,826</td><td>-423</td><td>41</td><td>-4</td></tr><tr><td>Total</td><td>$879,946</td><td>$-4,765</td><td>$4,202,856</td><td>$-84,220</td></tr><tr><td>December 31, 2005</td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. Treasury and federal agencies</td><td>$17,111</td><td>$-141</td><td>$302,942</td><td>$-7,638</td></tr><tr><td>Obligations of states and political subdivisions</td><td>55,830</td><td>-112</td><td>4,788</td><td>-23</td></tr><tr><td>Mortgage-backed securities:</td><td></td><td></td><td></td><td></td></tr><tr><td>Government issued or guaranteed</td><td>408,924</td><td>-7,754</td><td>1,693,319</td><td>-47,628</td></tr><tr><td>Privately issued</td><td>2,209,915</td><td>-23,252</td><td>1,121,380</td><td>-29,147</td></tr><tr><td>Other debt securities</td><td>16,587</td><td>-230</td><td>57,684</td><td>-903</td></tr><tr><td>Equity securities</td><td>134,266</td><td>-1,991</td><td>32</td><td>-11</td></tr><tr><td>Total</td><td>$2,842,633</td><td>$-33,480</td><td>$3,180,145</td><td>$-85,350</td></tr></table>
<table><tr><td></td><td> 2006</td><td> 2005</td></tr><tr><td></td><td colspan="2"> (In thousands)</td></tr><tr><td>December 31:</td><td></td><td></td></tr><tr><td>Gross unrealized gains</td><td>$82,864</td><td>$89,810</td></tr><tr><td>Gross unrealized losses</td><td>65,265</td><td>76,896</td></tr><tr><td>Year ended December 31:</td><td></td><td></td></tr><tr><td>Average gross unrealized gains</td><td>$96,041</td><td>$93,465</td></tr><tr><td>Average gross unrealized losses</td><td>80,626</td><td>82,389</td></tr></table>
<table><tr><td></td><td colspan="3">Year Ended December 31</td></tr><tr><td></td><td>2006</td><td>2005</td><td>2004</td></tr><tr><td></td><td colspan="3">(In thousands)</td></tr><tr><td>Revenues</td><td>$-70,789</td><td>$-70,698</td><td>$-60,195</td></tr><tr><td>Expenses</td><td>-20,760</td><td>-18,445</td><td>-16,950</td></tr><tr><td>Income taxes (benefit)</td><td>-20,357</td><td>-21,262</td><td>-17,596</td></tr><tr><td>Net income (loss)</td><td>-29,672</td><td>-30,991</td><td>-25,649</td></tr></table>
<table><tr><td><i>Millions</i></td><td><i>2012</i></td><td><i>2011</i></td><td><i>2010</i></td><td><i>% Change 2012 v 2011</i></td><td><i>% Change 2011 v 2010</i></td></tr><tr><td>Compensation and benefits</td><td>$4,685</td><td>$4,681</td><td>$4,314</td><td>-%</td><td>9%</td></tr><tr><td>Fuel</td><td>3,608</td><td>3,581</td><td>2,486</td><td>1</td><td>44</td></tr><tr><td>Purchased services and materials</td><td>2,143</td><td>2,005</td><td>1,836</td><td>7</td><td>9</td></tr><tr><td>Depreciation</td><td>1,760</td><td>1,617</td><td>1,487</td><td>9</td><td>9</td></tr><tr><td>Equipment and other rents</td><td>1,197</td><td>1,167</td><td>1,142</td><td>3</td><td>2</td></tr><tr><td>Other</td><td>788</td><td>782</td><td>719</td><td>1</td><td>9</td></tr><tr><td>Total</td><td>$14,181</td><td>$13,833</td><td>$11,984</td><td>3%</td><td>15%</td></tr></table>

Question: Which year is Other debt securities at Fair Value for Less Than 12 Months the least?