Risk management — The slight year-over-year decrease in 2010 and the consistent cost levels in 2009 and 2008 reflect the success we have had over the last several years in managing these costs, which can be credited primarily to our continued focus on safety and reduced accident and injury rates.
Other — The comparison of these costs has been significantly affected by the following: ?
In 2010, the increase in costs compared with 2009 was attributable, in part, to (i) our various growth and business development initiatives, (ii) oil spill clean-up activities along the Gulf Coast, and (iii) recently acquired businesses.
These cost increases were partially offset by an increase in gains recognized from the sale of surplus real estate assets.  ?
In 2009, we had a significant increase in the property taxes assessed for one of our waste-to-energy facilities.
Selling, General and Administrative Our selling, general and administrative expenses consist of (i) labor and related benefit costs, which include salaries, bonuses, related insurance and benefits, contract labor, payroll taxes and equity-based compensation; (ii) professional fees, which include fees for consulting, legal, audit and tax services; (iii) provision for bad debts, which includes allowances for uncollectible customer accounts and collection fees; and (iv) other selling, general and administrative expenses, which include, among other costs, facility-related expenses, voice and data telecommunication, advertising, travel and entertainment, rentals, postage and printing.
In addition, the financial impacts of litigation settlements generally are included in our “Other” selling, general and administrative expenses.
Our selling, general and administrative expenses increased by $97 million, or 7.1%, when comparing 2010 with 2009 and decreased $113 million, or 7.7%, when comparing 2009 with 2008.
The current year increase is largely due to (i) increased costs of $52 million during 2010, incurred to support our strategic plan to grow into new markets and provide expanded service offerings and (ii) increased costs of $23 million during 2010, resulting from improvements we are making to our information technology systems.
When comparing 2009 with 2008, the decrease was due in part to (i) the realization of benefits associated with our January 2009 restructuring and (ii) increased efforts to reduce controllable spending.
Our selling, general and administrative expenses as a percentage of revenues were 11.7% in 2010, 11.6% in 2009 and 11.0% in 2008.
The following table summarizes the major components of our selling, general and administrative costs for the years ended December 31 (dollars in millions):
## Table 0 ##
Labor and related benefits — In 2010, our labor and related benefits costs increased due primarily to (i) higher salaries and hourly wages due to merit increases; (ii) higher compensation costs due to an increase in headcount driven by our growth initiatives; (iii) additional bonus expense in 2010 because our performance against targets established by our annual incentive plans was stronger in 2010 compared with 2009; (iv) increased contract labor costs as a result of our current focus on optimizing our information technology systems; (v) increased severance costs; and (vi) higher non-cash compensation costs incurred for equity awards granted under our long-term incentive plans.
During the second quarter of 2009, we reversed all compensation costs previously recognized for our 2008 performance share units based on a determination that it was no longer probable that the targets established for that award would be met.
Additionally, stock option equity awards granted during the first quarter of 2010 provide for continued vesting for three years following an employee’s retirement, and because retirement-eligible employees are not required to provide any future service to vest in these awards, we recognized all of the compensation expense associated with their awards immediately.
We did not incur similar charges in prior years because this retirement provision was not included in any of the equity awards that were granted in 2009 or in 2008.
In 2009, our labor and related benefits costs decreased from 2008 because we realized benefits associated with our January 2009 restructuring.
Our labor and related benefits expenses in 2009 were also affected by a significant decrease in non-cash compensation costs associated with the equity-based compensation provided for by our longterm incentive plans as a result of (i) a decline in the grant-date fair value of our equity awards; (ii) lower performance against established targets for certain awards than in the prior year; and (iii) the reversal of all compensation costs previously recognized for our 2008 performance share units.
This decrease in non-cash compensation costs was offset, in part, by higher costs associated with our salary deferral plan, the costs of which are directly affected by equity-market conditions.
Additionally, contract labor costs incurred for various Corporate support functions were lower during 2009 than in 2008.
Professional fees — In 2010, our professional fees increased due to consulting fees, driven primarily by improvements we are making to our information technology systems and our continued strategic focus to grow into new markets and provide expanded service offerings.
This increase was partially offset by a reduction in legal fees in 2010.
Provision for bad debts — Our provision for bad debts was higher in 2009 and in 2008 as compared with 2010 as a result of the Company’s assessment of the weak economic environment in those years and the resulting impacts on our collection risk.
However, in the latter part of 2009 and during 2010 our collection risk moderated, thus resulting in a lower provision in 2010.
Other — During 2010, we experienced increases in our (i) litigation reserves, (ii) marketing and advertising costs, due in part to our strategic plan to grow into new markets and provide expanded service offerings, and (iii) computer costs, due in part to improvements we are making to our information technology systems.
In 2009, our focus on reducing controllable spending resulted in decreases in our advertising, meetings, seminars, and travel and entertainment costs.
These lower costs were partially due to the January 2009 restructuring.
This decline was offset partially by unfavorable litigation settlements in 2009.
Depreciation and Amortization Depreciation and amortization includes (i) depreciation of property and equipment, including assets recorded for capital leases, on a straight-line basis from three to 50 years; (ii) amortization of landfill costs, including those incurred and all estimated future costs for landfill development, construction and asset retirement costs arising from closure and post-closure, on a units-of-consumption method as landfill airspace is consumed over the total estimated remaining capacity of a site, which includes both permitted capacity and expansion capacity that meets our Company-specific criteria for amortization purposes; (iii) amortization of landfill asset retirement costs arising from capping obligations on a units-of-consumption method as airspace is consumed over the estimated capacity associated with each capping event; and (iv) amortization of intangible assets with a definite life, either using a 150% declining balance approach or a straight-line basis over the definitive terms of the related agreements, which are generally from two to ten years depending on the type of asset.
The following table summarizes the components of our depreciation and amortization costs for the years ended December 31 (dollars in millions):
## Table 1 ##
The increase in amortization expense of landfill airspace in 2010 is largely due to adjustments to the amortization rates at various landfill sites.
These adjustments were principally attributable to increases in cost estimates.
The decrease in amortization of landfill airspace expense in 2009 is largely due to volume declines as a
issuance of a note payable in return for a noncontrolling interest in a limited liability company established to invest in and manage low-income housing properties.
This investment is discussed in detail in Note 9.
For the years ended December 31, 2009 and 2008, these non-cash financing activities were primarily associated with our tax-exempt bond financings.
Proceeds from tax-exempt bond issuances, net of principal repayments made directly from trust funds, were $105 million in 2009 and $169 million in 2008.  ?
Other — Net cash provided by other financing activities was $18 million in 2010 while net cash used in other financing activities was $50 million in 2009 and $43 million in 2008.
These activities are primarily attributable to changes in our accrued liabilities for checks written in excess of cash balances due to the timing of cash deposits or payments.
The cash provided by these activities in 2010 was offset, in part, by $13 million of financing costs paid to execute our new $2.0 billion revolving credit facility.
Summary of Contractual Obligations The following table summarizes our contractual obligations as of December 31, 2010 and the anticipated effect of these obligations on our liquidity in future years (in millions):
## Table 2 ##
(a) Environmental liabilities include capping, closure, post-closure and environmental remediation costs.
The amounts included here reflect environmental liabilities recorded in our Consolidated Balance Sheet as of December 31, 2010 without the impact of discounting and inflation.
Our recorded environmental liabilities for capping, closure and post-closure will increase as we continue to place additional tons within the permitted airspace at our landfills.
(b) The amounts reported here represent the scheduled principal payments related to our long-term debt, excluding related interest.
Refer to Note 7 to the Consolidated Financial Statements for information regarding interest rates.
(c) Our debt obligations as of December 31, 2010 include $405 million of tax-exempt bonds subject to re-pricing within the next twelve months, which is prior to their scheduled maturities.
If the re-offerings of the bonds are unsuccessful, then the bonds can be put to us, requiring immediate repayment.
We have classified the anticipated cash flows for these contractual obligations based on the scheduled maturity of the borrowing for purposes of this disclosure.
For additional information regarding the classification of these borrowings in our Consolidated Balance Sheet as of December 31, 2010, refer to Note 7 to the Consolidated Financial Statements.
(d) Our recorded debt obligations include non-cash adjustments associated with discounts, premiums and fair value adjustments for interest rate hedging activities.
These amounts have been excluded here because they will not result in an impact to our liquidity in future periods.
(e) Our unrecorded obligations represent operating lease obligations and purchase commitments from which we expect to realize an economic benefit in future periods.
We have also made certain guarantees, as discussed in Note 11 to the Consolidated Financial Statements, that we do not expect to materially affect our current or future financial position, results of operations or liquidity

<table><tr><td></td><td> 2010</td><td colspan="2">Period-to- Period Change</td><td> 2009</td><td colspan="2">Period-to- Period Change</td><td> 2008</td></tr><tr><td>Labor and related benefits</td><td>$845</td><td>$70</td><td>9.0%</td><td>$775</td><td>$-78</td><td>-9.1%</td><td>$853</td></tr><tr><td>Professional fees</td><td>175</td><td>8</td><td>4.8</td><td>167</td><td>-1</td><td>-0.6</td><td>168</td></tr><tr><td>Provision for bad debts</td><td>45</td><td>-9</td><td>-16.7</td><td>54</td><td>-3</td><td>-5.3</td><td>57</td></tr><tr><td>Other</td><td>396</td><td>28</td><td>7.6</td><td>368</td><td>-31</td><td>-7.8</td><td>399</td></tr><tr><td></td><td>$1,461</td><td>$97</td><td>7.1%</td><td>$1,364</td><td>$-113</td><td>-7.7%</td><td>$1,477</td></tr></table>
<table><tr><td></td><td> 2010</td><td colspan="2">Period-to- Period Change</td><td> 2009</td><td colspan="2">Period-to- Period Change</td><td> 2008</td></tr><tr><td>Depreciation of tangible property and equipment</td><td>$781</td><td>$2</td><td>0.3%</td><td>$779</td><td>$-6</td><td>-0.8%</td><td>$785</td></tr><tr><td>Amortization of landfill airspace</td><td>372</td><td>14</td><td>3.9</td><td>358</td><td>-71</td><td>-16.6</td><td>429</td></tr><tr><td>Amortization of intangible assets</td><td>41</td><td>12</td><td>41.4</td><td>29</td><td>5</td><td>20.8</td><td>24</td></tr><tr><td></td><td>$1,194</td><td>$28</td><td>2.4%</td><td>$1,166</td><td>$-72</td><td>-5.8%</td><td>$1,238</td></tr></table>
<table><tr><td></td><td> 2011</td><td> 2012</td><td> 2013</td><td> 2014</td><td> 2015</td><td> Thereafter</td><td> Total</td></tr><tr><td> Recorded Obligations:</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Expected environmental liabilities(a)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Capping, closure and post-closure</td><td>$105</td><td>$116</td><td>$96</td><td>$102</td><td>$107</td><td>$1,943</td><td>$2,469</td></tr><tr><td>Environmental remediation</td><td>43</td><td>37</td><td>21</td><td>30</td><td>24</td><td>141</td><td>296</td></tr><tr><td></td><td>148</td><td>153</td><td>117</td><td>132</td><td>131</td><td>2,084</td><td>2,765</td></tr><tr><td>Debt payments(b),(c),(d)</td><td>511</td><td>614</td><td>203</td><td>459</td><td>452</td><td>6,600</td><td>8,839</td></tr><tr><td> Unrecorded Obligations:(e)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Non-cancelable operating lease obligations</td><td>82</td><td>76</td><td>62</td><td>51</td><td>40</td><td>215</td><td>526</td></tr><tr><td>Estimated unconditional purchase obligations(f)</td><td>85</td><td>84</td><td>58</td><td>21</td><td>16</td><td>238</td><td>502</td></tr><tr><td>Anticipated liquidity impact as of December 31, 2010</td><td>$826</td><td>$927</td><td>$440</td><td>$663</td><td>$639</td><td>$9,137</td><td>$12,632</td></tr></table>

Question: Which year is Capping, closure and post-closure the most?
Answer: 2012