certain mortgage loans citigroup has elected the fair value option for certain purchased and originated prime fixed-rate and conforming adjustable-rate first mortgage loans held-for-sale . these loans are intended for sale or securitization and are hedged with derivative instruments . the company has elected the fair value option to mitigate accounting mismatches in cases where hedge .
what was the percentage decline in aggregate fair value in excess of unpaid principal balance for the loans accounted for with the fair value option from 2008 to 2009
the changes in fair values of these mortgage loans are reported in other revenue in the company 2019s consolidated statement of income . the changes in fair value during the years ended december 31 , 2009 and 2008 due to instrument-specific credit risk resulted in a $ 10 million loss and $ 32 million loss , respectively . related interest income continues to be measured based on the contractual interest rates and reported as such in the consolidated statement of income . mortgage servicing rights the company accounts for mortgage servicing rights ( msrs ) at fair value . fair value for msrs is determined using an option-adjusted spread valuation approach . this approach consists of projecting servicing cash flows under multiple interest-rate scenarios and discounting these cash flows using risk-adjusted rates . the model assumptions used in the valuation of msrs include mortgage prepayment speeds and discount rates . the fair value of msrs is primarily affected by changes in prepayments that result from shifts in mortgage interest rates . in managing this risk , the company hedges a significant portion of the values of its msrs through the use of interest-rate derivative contracts , forward-purchase commitments of mortgage-backed securities , and purchased securities classified as trading . see note 23 to the consolidated financial statements for further discussions regarding the accounting and reporting of msrs . these msrs , which totaled $ 6.5 billion and $ 5.7 billion as of december 31 , 2009 and 2008 , respectively , are classified as mortgage servicing rights on citigroup 2019s consolidated balance sheet . changes in fair value of msrs are recorded in commissions and fees in the company 2019s consolidated statement of income . certain structured liabilities the company has elected the fair value option for certain structured liabilities whose performance is linked to structured interest rates , inflation or currency risks ( 201cstructured liabilities 201d ) . the company elected the fair value option , because these exposures are considered to be trading-related positions and , therefore , are managed on a fair value basis . these positions will continue to be classified as debt , deposits or derivatives ( trading account liabilities ) on the company 2019s consolidated balance sheet according to their legal form . for those structured liabilities classified as long-term debt for which the fair value option has been elected , the aggregate unpaid principal balance exceeded the aggregate fair value by $ 125 million and $ 671 million as of december 31 , 2009 and 2008 , respectively . the change in fair value for these structured liabilities is reported in principal transactions in the company 2019s consolidated statement of income . related interest expense is measured based on the contractual interest rates and reported as such in the consolidated income statement . certain non-structured liabilities the company has elected the fair value option for certain non-structured liabilities with fixed and floating interest rates ( 201cnon-structured liabilities 201d ) . the company has elected the fair value option where the interest-rate risk of such liabilities is economically hedged with derivative contracts or the proceeds are used to purchase financial assets that will also be accounted for at fair value through earnings . the election has been made to mitigate accounting mismatches and to achieve operational simplifications . these positions are reported in short-term borrowings and long-term debt on the company 2019s consolidated balance sheet . for those non-structured liabilities classified as short-term borrowings for which the fair value option has been elected , the aggregate unpaid principal balance exceeded the aggregate fair value of such instruments by $ 220 million as of december 31 , 2008 . for non-structured liabilities classified as long-term debt for which the fair value option has been elected , the aggregate unpaid principal balance exceeded the aggregate fair value by $ 1542 million and $ 856 million as of december 31 , 2009 and 2008 , respectively . the change in fair value for these non-structured liabilities is reported in principal transactions in the company 2019s consolidated statement of income . related interest expense continues to be measured based on the contractual interest rates and reported as such in the consolidated income statement . accounting is complex and to achieve operational simplifications . the fair value option was not elected for loans held-for-investment , as those loans are not hedged with derivative instruments . the following table provides information about certain mortgage loans carried at fair value: .