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 . the majority of these non-structured liabilities are a result of the company 2019s election of the fair-value option for liabilities associated with the citi-advised structured investment vehicles ( sivs ) , which were consolidated during the fourth quarter of 2007 . the change in fair values of the sivs 2019 liabilities reported in earnings was $ 2.6 billion for the year ended december 31 , 2008 . for these non-structured liabilities the aggregate fair value is $ 263 million lower than the aggregate unpaid principal balance as of december 31 , 2008 . for all other non-structured liabilities classified as long-term debt for which the fair-value option has been elected , the aggregate unpaid principal balance exceeds the aggregate fair value of such instruments by $ 97 million as of december 31 , 2008 while the aggregate fair value exceeded the aggregate unpaid principal by $ 112 million as of december 31 , 2007 . the change in fair value of these non-structured liabilities reported a gain of $ 1.2 billion for the year ended december 31 , 2008 . 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 . 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 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 . this election was effective for applicable instruments originated or purchased on or after september 1 , 2007 . the following table provides information about certain mortgage loans carried at fair value : in millions of dollars december 31 , december 31 , carrying amount reported on the consolidated balance sheet $ 4273 $ 6392 aggregate fair value in excess of unpaid principal balance $ 138 $ 136 balance on non-accrual loans or loans more than 90 days past due $ 9 $ 17 aggregate unpaid principal balance in excess of fair value for non-accrual loans or loans more than 90 days past due $ 2 $ 2014 the changes in fair values of these mortgage loans is reported in other revenue in the company 2019s consolidated statement of income . the changes in fair value during the year ended december 31 , 2008 due to instrument- specific credit risk resulted in a $ 32 million loss . the change in fair value during 2007 due to instrument-specific credit risk was immaterial . related interest income continues to be measured based on the contractual interest rates and reported as such in the consolidated income statement . items selected for fair-value accounting in accordance with sfas 155 and sfas 156 certain hybrid financial instruments the company has elected to apply fair-value accounting under sfas 155 for certain hybrid financial assets and liabilities whose performance is linked to risks other than interest rate , foreign exchange or inflation ( e.g. , equity , credit or commodity risks ) . in addition , the company has elected fair-value accounting under sfas 155 for residual interests retained from securitizing certain financial assets . the company has elected fair-value accounting for these instruments because these exposures are considered to be trading-related positions and , therefore , are managed on a fair-value basis . in addition , the accounting for these instruments is simplified under a fair-value approach as it eliminates the complicated operational requirements of bifurcating the embedded derivatives from the host contracts and accounting for each separately . the hybrid financial instruments are classified as trading account assets , loans , deposits , trading account liabilities ( for prepaid derivatives ) , short-term borrowings or long-term debt on the company 2019s consolidated balance sheet according to their legal form , while residual interests in certain securitizations are classified as trading account assets . for hybrid financial instruments for which fair-value accounting has been elected under sfas 155 and that are classified as long-term debt , the aggregate unpaid principal exceeds the aggregate fair value by $ 1.9 billion as of december 31 , 2008 , while the aggregate fair value exceeds the aggregate unpaid principal balance by $ 460 million as of december 31 , 2007 . the difference for those instruments classified as loans is immaterial . changes in fair value for hybrid financial instruments , which in most cases includes a component for accrued interest , are recorded in principal transactions in the company 2019s consolidated statement of income . interest accruals for certain hybrid instruments classified as trading assets are recorded separately from the change in fair value as interest revenue in the company 2019s consolidated statement of income . mortgage servicing rights the company accounts for mortgage servicing rights ( msrs ) at fair value in accordance with sfas 156 . 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 on page 175 for further discussions regarding the accounting and reporting of msrs . these msrs , which totaled $ 5.7 billion and $ 8.4 billion as of december 31 , 2008 and december 31 , 2007 , 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. .

december 31 2008: carrying amount reported on the consolidated balance sheet: 4273
aggregate fair value in excess of unpaid principal balance: 138
balance on non-accrual loans or loans more than 90 days past due: 9
aggregate unpaid principal balance in excess of fair value for non-accrual loans or loans more than 90 days pastdue: 2
december 31 2007: carrying amount reported on the consolidated balance sheet: 6392
aggregate fair value in excess of unpaid principal balance: 136
balance on non-accrual loans or loans more than 90 days past due: 17
aggregate unpaid principal balance in excess of fair value for non-accrual loans or loans more than 90 days pastdue: 2014

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 . the majority of these non-structured liabilities are a result of the company 2019s election of the fair-value option for liabilities associated with the citi-advised structured investment vehicles ( sivs ) , which were consolidated during the fourth quarter of 2007 . the change in fair values of the sivs 2019 liabilities reported in earnings was $ 2.6 billion for the year ended december 31 , 2008 . for these non-structured liabilities the aggregate fair value is $ 263 million lower than the aggregate unpaid principal balance as of december 31 , 2008 . for all other non-structured liabilities classified as long-term debt for which the fair-value option has been elected , the aggregate unpaid principal balance exceeds the aggregate fair value of such instruments by $ 97 million as of december 31 , 2008 while the aggregate fair value exceeded the aggregate unpaid principal by $ 112 million as of december 31 , 2007 . the change in fair value of these non-structured liabilities reported a gain of $ 1.2 billion for the year ended december 31 , 2008 . 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 . 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 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 . this election was effective for applicable instruments originated or purchased on or after september 1 , 2007 . the following table provides information about certain mortgage loans carried at fair value : in millions of dollars december 31 , december 31 , carrying amount reported on the consolidated balance sheet $ 4273 $ 6392 aggregate fair value in excess of unpaid principal balance $ 138 $ 136 balance on non-accrual loans or loans more than 90 days past due $ 9 $ 17 aggregate unpaid principal balance in excess of fair value for non-accrual loans or loans more than 90 days past due $ 2 $ 2014 the changes in fair values of these mortgage loans is reported in other revenue in the company 2019s consolidated statement of income . the changes in fair value during the year ended december 31 , 2008 due to instrument- specific credit risk resulted in a $ 32 million loss . the change in fair value during 2007 due to instrument-specific credit risk was immaterial . related interest income continues to be measured based on the contractual interest rates and reported as such in the consolidated income statement . items selected for fair-value accounting in accordance with sfas 155 and sfas 156 certain hybrid financial instruments the company has elected to apply fair-value accounting under sfas 155 for certain hybrid financial assets and liabilities whose performance is linked to risks other than interest rate , foreign exchange or inflation ( e.g. , equity , credit or commodity risks ) . in addition , the company has elected fair-value accounting under sfas 155 for residual interests retained from securitizing certain financial assets . the company has elected fair-value accounting for these instruments because these exposures are considered to be trading-related positions and , therefore , are managed on a fair-value basis . in addition , the accounting for these instruments is simplified under a fair-value approach as it eliminates the complicated operational requirements of bifurcating the embedded derivatives from the host contracts and accounting for each separately . the hybrid financial instruments are classified as trading account assets , loans , deposits , trading account liabilities ( for prepaid derivatives ) , short-term borrowings or long-term debt on the company 2019s consolidated balance sheet according to their legal form , while residual interests in certain securitizations are classified as trading account assets . for hybrid financial instruments for which fair-value accounting has been elected under sfas 155 and that are classified as long-term debt , the aggregate unpaid principal exceeds the aggregate fair value by $ 1.9 billion as of december 31 , 2008 , while the aggregate fair value exceeds the aggregate unpaid principal balance by $ 460 million as of december 31 , 2007 . the difference for those instruments classified as loans is immaterial . changes in fair value for hybrid financial instruments , which in most cases includes a component for accrued interest , are recorded in principal transactions in the company 2019s consolidated statement of income . interest accruals for certain hybrid instruments classified as trading assets are recorded separately from the change in fair value as interest revenue in the company 2019s consolidated statement of income . mortgage servicing rights the company accounts for mortgage servicing rights ( msrs ) at fair value in accordance with sfas 156 . 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 on page 175 for further discussions regarding the accounting and reporting of msrs . these msrs , which totaled $ 5.7 billion and $ 8.4 billion as of december 31 , 2008 and december 31 , 2007 , 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. .

Questions:
what was the fair value of the msr in 2008?
and what was it in 2007?
what was, then, the change over the year?
what was the fair value of the msr in 2007?
and how much does that change represent in relation to this 2007 fair value, in percentage?

Answers:
4273
6392
-2119
6392
-33.2%