interest-earning assets including unearned income in the accretion of fair value adjustments on discounts recognized on acquired or purchased loans is recognized based on the constant effective yield of the financial instrument.
The timing and amount of revenue that we recognize in any period is dependent on estimates, judgments, assumptions, and interpretation of contractual terms.
Changes in these factors can have a significant impact on revenue recognized in any period due to changes in products, market conditions or industry norms.
Residential And Commercial Mortgage Servicing Rights We elect to measure our residential mortgage servicing rights (MSRs) at fair value.
This election was made to be consistent with our risk management strategy to hedge changes in the fair value of these assets as described below.
The fair value of residential MSRs is estimated by using a cash flow valuation model which calculates the present value of estimated future net servicing cash flows, taking into consideration actual and expected mortgage loan prepayment rates, discount rates, servicing costs, and other economic factors which are determined based on current market conditions.
Assumptions incorporated into the residential MSRs valuation model reflect management’s best estimate of factors that a market participant would use in valuing the residential MSRs.
Although sales of residential MSRs do occur, residential MSRs do not trade in an active market with readily observable prices so the precise terms and conditions of sales are not available.
As a benchmark for the reasonableness of its residential MSRs fair value, PNC obtains opinions of value from independent parties (“brokers”).
These brokers provided a range (+/- 10 bps) based upon their own discounted cash flow calculations of our portfolio that reflected conditions in the secondary market, and any recently executed servicing transactions.
PNC compares its internally-developed residential MSRs value to the ranges of values received from the brokers.
If our residential MSRs fair value falls outside of the brokers’ ranges, management will assess whether a valuation adjustment is warranted.
For 2011 and 2010, PNC’s residential MSRs value has not fallen outside of the brokers’ ranges.
We consider our residential MSRs value to represent a reasonable estimate of fair value.
Commercial MSRs are purchased or originated when loans are sold with servicing retained.
Commercial MSRs do not trade in an active market with readily observable prices so the precise terms and conditions of sales are not available.
Commercial MSRs are initially recorded at fair value and are subsequently accounted for at the lower of amortized cost or fair value.
Commercial MSRs are periodically evaluated for impairment.
For purposes of impairment, the commercial mortgage servicing rights are stratified based on asset type, which characterizes the predominant risk of the underlying financial asset.
The fair value of commercial MSRs is estimated by using an internal valuation model.
The model calculates the present value of estimated future net servicing cash flows considering estimates of servicing revenue and costs, discount rates and prepayment speeds.
PNC employs risk management strategies designed to protect the value of MSRs from changes in interest rates and related market factors.
Residential MSRs values are economically hedged with securities and derivatives, including interest-rate swaps, options, and forward mortgage-backed and futures contracts.
As interest rates change, these financial instruments are expected to have changes in fair value negatively correlated to the change in fair value of the hedged residential MSRs portfolio.
The hedge relationships are actively managed in response to changing market conditions over the life of the residential MSRs assets.
Commercial MSRs are economically hedged at a macro level or with specific derivatives to protect against a significant decline in interest rates.
Selecting appropriate financial instruments to economically hedge residential or commercial MSRs requires significant management judgment to assess how mortgage rates and prepayment speeds could affect the future values of MSRs.
Hedging results can frequently be less predictable in the short term, but over longer periods of time are expected to protect the economic value of the MSRs.
The fair value of residential and commercial MSRs and significant inputs to the valuation model as of December 31, 2011 are shown in the tables below.
The expected and actual rates of mortgage loan prepayments are significant factors driving the fair value.
Management uses a third-party model to estimate future residential loan prepayments and internal proprietary models to estimate future commercial loan prepayments.
These models have been refined based on current market conditions.
Future interest rates are another important factor in the valuation of MSRs.
Management utilizes market implied forward interest rates to estimate the future direction of mortgage and discount rates.
The forward rates utilized are derived from the current yield curve for U. S.  dollar interest rate swaps and are consistent with pricing of capital markets instruments.
Changes in the shape and slope of the forward curve in future periods may result in volatility in the fair value estimate.
Residential Mortgage Servicing Rights
## Table 0 ##
(a) Changes in weighted-average life and weighted-average constant prepayment rate reflect the cumulative impact of changes in rates, prepayment expectations and model changes.
Accruing Loans Past Due 90 Days Or More
## Table 1 ##
Our Special Asset Committee closely monitors primarily commercial loans that are not included in the nonperforming or accruing past due categories and for which we are uncertain about the borrower’s ability to comply with existing repayment terms over the next six months.
These loans totaled $438 million at December 31, 2011 and $574 million at December 31, 2010.
Home Equity Loan Portfolio Our home equity loan portfolio totaled $33.1 billion as of December 31, 2011, or 21% of the total loan portfolio.
Of that total, $22.5 billion, or 68%, was outstanding under primarily variable-rate home equity lines of credit and $10.6 billion, or 32%, consisted of closed-end home equity installment loans.
Less than 2% of the home equity portfolio was on nonperforming status as of December 31, 2011.
As of December 31, 2011, we are in an originated first lien position for approximately 33% of the total portfolio and, where originated as a second lien, we currently hold or service the first lien position for approximately an additional 2% of the portfolio.
Historically, we have originated and sold first mortgages which has resulted in a low percentage of home equity loans where we hold the first lien mortgage position.
The remaining 65% of the portfolio was secured by second liens where we do not hold the first lien position.
For the majority of the home equity portfolio where we are in, hold or service the first lien position, the credit performance of this portion of the portfolio is superior to the portion of the portfolio where we hold the second lien position but do not hold the first lien.
Subsequent to origination, PNC is not typically notified when a senior lien position that is not held by PNC is satisfied.
Therefore, information about the current lien status of the loans is limited, for loans that were originated in subordinated lien positions where PNC does not also hold the senior lien, to what can be obtained from external sources.
PNC contracted with a third-party service provider to provide updated loan, lien and collateral data that is aggregated from public and private sources.
We started receiving the data in late 2011 and we are working with the third-party provider to enhance the information we are receiving.
As we have made progress in our efforts, we have incrementally enhanced our risk management processes and reporting to incorporate this updated loan, lien, and collateral data, and we anticipate being substantially complete by the end of second quarter 2012.
We track borrower performance monthly and other credit metrics at least quarterly, including historical performance of any mortgage loans regardless of lien position that we may or may not hold, updated FICO scores and original and updated LTVs.
This information is used for internal risk management reporting and monitoring.
We segment the population into pools based on product type (e. g. , home equity loans, brokered home equity loans, home equity lines of credit, brokered home equity lines of credit).
We also further segment certain loans based upon the delinquency status of any mortgage loan with the same borrower (regardless of whether it is a first lien senior to our second lien).
In establishing our ALLL, we utilize a delinquency roll-rate methodology for pools of loans.
In accordance with accounting principles, under this methodology, we establish our allowance based upon incurred losses and not lifetime expected losses.
The roll-rate methodology estimates transition/roll of loan balances from one delinquency state (e. g. , 30-59 days past due) to another delinquency state (e. g. , 60-89 days past due) and ultimately charge-off.
The roll through to charge-off is based on PNC’s actual loss experience for each type of pool.
Since a pool may consist of first and second liens, the charge-off amounts for the pool are proportionate to the composition of first and second liens in the pool.
Our experience has been that the ratio of first to second lien loans has been consistent over time and is appropriately represented in our pools used for roll-rate calculations.
by the U. S.  banking agencies, and final rules issued by the Federal Reserve that make certain modifications to the Federal Reserve’s capital planning and stress testing rules.
See Table 37 for information on an affiliate purchase of notes issued by PNC Bank during 2015.
Parent Company Liquidity – Sources The principal source of parent company liquidity is the dividends it receives from its subsidiary bank, which may be impacted by the following: ?
Bank-level capital needs, ?
Laws and regulations, ?
Corporate policies, ?
Contractual restrictions, and ?
Other factors.
There are statutory and regulatory limitations on the ability of a national bank to pay dividends or make other capital distributions or to extend credit to the parent company or its non-bank subsidiaries.
The amount available for dividend payments by PNC Bank to the parent company without prior regulatory approval was approximately $1.7 billion at December 31, 2015.
See Note 19 Regulatory Matters in the Notes To Consolidated Financial Statements in Item 8 of this Report for a further discussion of these limitations.
We provide additional information on certain contractual restrictions in Note 16 Equity in the Notes To Consolidated Financial Statements in Item 8 of this Report.
In addition to dividends from PNC Bank, other sources of parent company liquidity include cash and investments, as well as dividends and loan repayments from other subsidiaries and dividends or distributions from equity investments.
We can also generate liquidity for the parent company and PNC’s non-bank subsidiaries through the issuance of debt and equity securities, including certain capital instruments, in public or private markets and commercial paper.
Total parent company senior and subordinated debt and hybrid capital instruments decreased to $7.5 billion at December 31, 2015 from $10.1 billion at December 31, 2014 due to the following activity in the period.
Table 40: Parent Company Senior and Subordinated Debt and Hybrid Capital Instruments
## Table 2 ##
The parent company has the ability to offer up to $5.0 billion of commercial paper to provide additional liquidity.
As of December 31, 2015, there were no issuances outstanding under this program.
Status of Credit Ratings The cost and availability of short-term and long-term funding, as well as collateral requirements for certain derivative instruments, is influenced by PNC’s credit ratings.
In general, rating agencies base their ratings on many quantitative and qualitative factors, including capital adequacy, liquidity, asset quality, business mix, level and quality of earnings, and the current legislative and regulatory environment, including implied government support.
In addition, rating agencies themselves have been subject to scrutiny arising from the most recent financial crisis and could make or be required to make substantial changes to their ratings policies and practices, particularly in response to legislative and regulatory changes.
Potential changes in the legislative and regulatory environment and the timing of those changes could impact our ratings, which as noted above, could impact our liquidity and financial condition.
A decrease, or potential decrease, in credit ratings could impact access to the capital markets and/or increase the cost of debt, and thereby adversely affect liquidity and financial condition.
In March 2015, Moody’s Investors Service (Moody’s) published a new bank ratings methodology which has been implemented on a global basis and includes assessment of expected loss ratings on instruments ranging from bank deposits to preferred stock.
In the second quarter of 2015, Moody’s concluded its review for PNC and PNC Bank under this new methodology.
As a result, Moody’s upgraded PNC Bank’s long-term deposit rating three notches to Aa2, confirmed PNC Bank’s senior debt and issuer ratings at A2, and confirmed PNC Bank’s Prime-1 short-term notes rating.
The Moody’s rating outlook for PNC and PNC Bank is stable.
Table 41: Credit Ratings as of December 31, 2015 for PNC and PNC Bank

Tables referenced above, in order (Table 0 first):
<table><tr><td>Dollars in millions</td><td>December 31 2011</td><td>December 312010</td></tr><tr><td>Fair value</td><td>$647</td><td>$1,033</td></tr><tr><td>Weighted-average life (in years) (a)</td><td>3.6</td><td>5.8</td></tr><tr><td>Weighted-average constant prepayment rate (a)</td><td>22.10%</td><td>12.61%</td></tr><tr><td>Weighted-average option adjusted spread</td><td>11.77%</td><td>12.18%</td></tr></table>
<table><tr><td></td><td colspan="2">Amount</td><td colspan="2">Percent of Total Outstandings</td></tr><tr><td>Dollars in millions</td><td> Dec. 31 2011</td><td>Dec. 31 2010</td><td>Dec. 31 2011</td><td>Dec. 31 2010</td></tr><tr><td>Commercial</td><td>$49</td><td>$59</td><td>.07%</td><td>.11%</td></tr><tr><td>Commercial real estate</td><td>6</td><td>43</td><td>.04</td><td>.24</td></tr><tr><td>Equipment lease financing</td><td></td><td>1</td><td></td><td>.02</td></tr><tr><td>Home equity</td><td>221</td><td>174</td><td>.67</td><td>.51</td></tr><tr><td>Residential real estate</td><td></td><td></td><td></td><td></td></tr><tr><td>Non government insured</td><td>152</td><td>160</td><td>1.05</td><td>1.00</td></tr><tr><td>Government insured</td><td>2,129</td><td>1,961</td><td>14.71</td><td>12.26</td></tr><tr><td>Credit card</td><td>48</td><td>77</td><td>1.21</td><td>1.96</td></tr><tr><td>Other consumer</td><td></td><td></td><td></td><td></td></tr><tr><td>Non government insured</td><td>23</td><td>28</td><td>.12</td><td>.16</td></tr><tr><td>Government insured</td><td>345</td><td>206</td><td>1.80</td><td>1.22</td></tr><tr><td>Total</td><td>$2,973</td><td>$2,709</td><td>1.87</td><td>1.80</td></tr></table>
<table><tr><td>In billions</td><td>2015</td></tr><tr><td>January 1</td><td>$10.1</td></tr><tr><td>Maturities</td><td>-2.5</td></tr><tr><td>Other</td><td>-.1</td></tr><tr><td>December 31</td><td>$7.5</td></tr></table>

Question: What is the difference between the greatest Commercial in 2011 and 2010 ? (in million)
Answer: 10
Reasoning program: subtract(59,49)