special asset pool special asset pool ( sap ) , which constituted approximately 22% ( 22 % ) of citi holdings by assets as of december 31 , 2010 , is a portfolio of securities , loans and other assets that citigroup intends to actively reduce over time through asset sales and portfolio run-off . at december 31 , 2010 , sap had $ 80 billion of assets . sap assets have declined by $ 248 billion , or 76% ( 76 % ) , from peak levels in 2007 reflecting cumulative write-downs , asset sales and portfolio run-off . in millions of dollars 2010 2009 2008 % (  % ) change 2010 vs . 2009 % (  % ) change 2009 vs . 2008 .
what percentage of revenue net of interest expense is due to net interest revenue in 2010?
nm not meaningful 2010 vs . 2009 revenues , net of interest expense increased $ 6.1 billion , primarily due to the improvement of revenue marks in 2010 . aggregate marks were negative $ 2.6 billion in 2009 as compared to positive marks of $ 3.4 billion in 2010 ( see 201citems impacting sap revenues 201d below ) . revenue in the current year included positive marks of $ 2.0 billion related to sub-prime related direct exposure , a positive $ 0.5 billion cva related to the monoline insurers , and $ 0.4 billion on private equity positions . these positive marks were partially offset by negative revenues of $ 0.5 billion on alt-a mortgages and $ 0.4 billion on commercial real estate . operating expenses decreased 33% ( 33 % ) in 2010 , mainly driven by the absence of the u.s . government loss-sharing agreement , lower compensation , and lower transaction expenses . provisions for credit losses and for benefits and claims decreased $ 4.8 billion due to a decrease in net credit losses of $ 3.4 billion and a higher release of loan loss reserves and unfunded lending commitments of $ 1.4 billion . assets declined 41% ( 41 % ) from the prior year , primarily driven by sales and amortization and prepayments . asset sales of $ 39 billion for the year of 2010 generated pretax gains of approximately $ 1.3 billion . 2009 vs . 2008 revenues , net of interest expense increased $ 36.4 billion in 2009 , primarily due to the absence of significant negative revenue marks occurring in the prior year . total negative marks were $ 2.6 billion in 2009 as compared to $ 37.4 billion in 2008 . revenue in 2009 included positive marks of $ 0.8 billion on subprime-related direct exposures . these positive revenues were partially offset by negative revenues of $ 1.5 billion on alt-a mortgages , $ 0.8 billion of write-downs on commercial real estate , and a negative $ 1.6 billion cva on the monoline insurers and fair value option liabilities . revenue was also affected by negative marks on private equity positions and write-downs on highly leveraged finance commitments . operating expenses decreased 8% ( 8 % ) in 2009 , mainly driven by lower compensation and lower volumes and transaction expenses , partially offset by costs associated with the u.s . government loss-sharing agreement exited in the fourth quarter of 2009 . provisions for credit losses and for benefits and claims increased $ 1.6 billion , primarily driven by $ 4.5 billion in increased net credit losses , partially offset by a lower provision for loan losses and unfunded lending commitments of $ 2.9 billion . assets declined 38% ( 38 % ) versus the prior year , primarily driven by amortization and prepayments , sales , marks and charge-offs. .