on-balance sheet securitizations the company engages in on-balance sheet securitizations . these are securitizations that do not qualify for sales treatment ; thus , the assets remain on the company 2019s balance sheet . the following table presents the carrying amounts and classification of consolidated assets and liabilities transferred in transactions from the consumer credit card , student loan , mortgage and auto businesses , accounted for as secured borrowings : in billions of dollars december 31 , december 31 .
what was the change in billions of the available-for-sale securities between 2007 and 2008?
all assets are restricted from being sold or pledged as collateral . the cash flows from these assets are the only source used to pay down the associated liabilities , which are non-recourse to the company 2019s general assets . citi-administered asset-backed commercial paper conduits the company is active in the asset-backed commercial paper conduit business as administrator of several multi-seller commercial paper conduits , and also as a service provider to single-seller and other commercial paper conduits sponsored by third parties . the multi-seller commercial paper conduits are designed to provide the company 2019s customers access to low-cost funding in the commercial paper markets . the conduits purchase assets from or provide financing facilities to customers and are funded by issuing commercial paper to third-party investors . the conduits generally do not purchase assets originated by the company . the funding of the conduit is facilitated by the liquidity support and credit enhancements provided by the company and by certain third parties . as administrator to the conduits , the company is responsible for selecting and structuring of assets purchased or financed by the conduits , making decisions regarding the funding of the conduits , including determining the tenor and other features of the commercial paper issued , monitoring the quality and performance of the conduits 2019 assets , and facilitating the operations and cash flows of the conduits . in return , the company earns structuring fees from clients for individual transactions and earns an administration fee from the conduit , which is equal to the income from client program and liquidity fees of the conduit after payment of interest costs and other fees . this administration fee is fairly stable , since most risks and rewards of the underlying assets are passed back to the customers and , once the asset pricing is negotiated , most ongoing income , costs and fees are relatively stable as a percentage of the conduit 2019s size . the conduits administered by the company do not generally invest in liquid securities that are formally rated by third parties . the assets are privately negotiated and structured transactions that are designed to be held by the conduit , rather than actively traded and sold . the yield earned by the conduit on each asset is generally tied to the rate on the commercial paper issued by the conduit , thus passing interest rate risk to the client . each asset purchased by the conduit is structured with transaction-specific credit enhancement features provided by the third-party seller , including over- collateralization , cash and excess spread collateral accounts , direct recourse or third-party guarantees . these credit enhancements are sized with the objective of approximating a credit rating of a or above , based on the company 2019s internal risk ratings . substantially all of the funding of the conduits is in the form of short- term commercial paper . as of december 31 , 2008 , the weighted average life of the commercial paper issued was approximately 37 days . in addition , the conduits have issued subordinate loss notes and equity with a notional amount of approximately $ 80 million and varying remaining tenors ranging from six months to seven years . the primary credit enhancement provided to the conduit investors is in the form of transaction-specific credit enhancement described above . in addition , there are two additional forms of credit enhancement that protect the commercial paper investors from defaulting assets . first , the subordinate loss notes issued by each conduit absorb any credit losses up to their full notional amount . it is expected that the subordinate loss notes issued by each conduit are sufficient to absorb a majority of the expected losses from each conduit , thereby making the single investor in the subordinate loss note the primary beneficiary under fin 46 ( r ) . second , each conduit has obtained a letter of credit from the company , which is generally 8-10% ( 8-10 % ) of the conduit 2019s assets . the letters of credit provided by the company total approximately $ 5.8 billion and are included in the company 2019s maximum exposure to loss . the net result across all multi-seller conduits administered by the company is that , in the event of defaulted assets in excess of the transaction-specific credit enhancement described above , any losses in each conduit are allocated in the following order : 2022 subordinate loss note holders 2022 the company 2022 the commercial paper investors the company , along with third parties , also provides the conduits with two forms of liquidity agreements that are used to provide funding to the conduits in the event of a market disruption , among other events . each asset of the conduit is supported by a transaction-specific liquidity facility in the form of an asset purchase agreement ( apa ) . under the apa , the company has agreed to purchase non-defaulted eligible receivables from the conduit at par . any assets purchased under the apa are subject to increased pricing . the apa is not designed to provide credit support to the conduit , as it generally does not permit the purchase of defaulted or impaired assets and generally reprices the assets purchased to consider potential increased credit risk . the apa covers all assets in the conduits and is considered in the company 2019s maximum exposure to loss . in addition , the company provides the conduits with program-wide liquidity in the form of short-term lending commitments . under these commitments , the company has agreed to lend to the conduits in the event of a short-term disruption in the commercial paper market , subject to specified conditions . the total notional exposure under the program-wide liquidity agreement is $ 11.3 billion and is considered in the company 2019s maximum exposure to loss . the company receives fees for providing both types of liquidity agreement and considers these fees to be on fair market terms. .