expenditures and acquisitions of leased properties are funded by the original contributor of the assets , but no change in ownership interest may result from these contributions . an excess of ashland funded improvements over marathon funded improvements results in a net gain and an excess of marathon funded improvements over ashland funded improvements results in a net loss . cost of revenues increased by $ 8.718 billion in 2003 from 2002 and $ 367 million in 2002 from 2001 . the increases in the oerb segment were primarily a result of higher natural gas and liquid hydrocarbon costs . the increases in the rm&t segment primarily reflected higher acquisition costs for crude oil , refined products , refinery charge and blend feedstocks and increased manufacturing expenses . selling , general and administrative expenses increased by $ 107 million in 2003 from 2002 and $ 125 million in 2002 from 2001 . the increase in 2003 was primarily a result of increased employee benefits ( caused by increased pension expense resulting from changes in actuarial assumptions and a decrease in realized returns on plan assets ) and other employee related costs . also , marathon changed assumptions in the health care cost trend rate from 7.5% ( 7.5 % ) to 10% ( 10 % ) , resulting in higher retiree health care costs . additionally , during 2003 , marathon recorded a charge of $ 24 million related to organizational and business process changes . the increase in 2002 primarily reflected increased employee related costs . inventory market valuation reserve is established to reduce the cost basis of inventories to current market value . the 2002 results of operations include credits to income from operations of $ 71 million , reversing the imv reserve at december 31 , 2001 . for additional information on this adjustment , see 201cmanagement 2019s discussion and analysis of critical accounting estimates 2013 net realizable value of inventories 201d on page 31 . net interest and other financial costs decreased by $ 82 million in 2003 from 2002 , following an increase of $ 96 million in 2002 from 2001 . the decrease in 2003 is primarily due to an increase in capitalized interest related to increased long-term construction projects , the favorable effect of interest rate swaps , the favorable effect of interest on tax deficiencies and increased interest income on investments . the increase in 2002 was primarily due to higher average debt levels resulting from acquisitions and the separation . additionally , included in net interest and other financing costs are foreign currency gains of $ 13 million and $ 8 million for 2003 and 2002 and losses of $ 5 million for 2001 . loss from early extinguishment of debt in 2002 was attributable to the retirement of $ 337 million aggregate principal amount of debt , resulting in a loss of $ 53 million . as a result of the adoption of statement of financial accounting standards no . 145 201crescission of fasb statements no . 4 , 44 , and 64 , amendment of fasb statement no . 13 , and technical corrections 201d ( 201csfas no . 145 201d ) , the loss from early extinguishment of debt that was previously reported as an extraordinary item ( net of taxes of $ 20 million ) has been reclassified into income before income taxes . the adoption of sfas no . 145 had no impact on net income for 2002 . minority interest in income of map , which represents ashland 2019s 38 percent ownership interest , increased by $ 129 million in 2003 from 2002 , following a decrease of $ 531 million in 2002 from 2001 . map income was higher in 2003 compared to 2002 as discussed below in the rm&t segment . map income was significantly lower in 2002 compared to 2001 as discussed below in the rm&t segment . provision for income taxes increased by $ 215 million in 2003 from 2002 , following a decrease of $ 458 million in 2002 from 2001 , primarily due to $ 720 million increase and $ 1.356 billion decrease in income before income taxes . the effective tax rate for 2003 was 36.6% ( 36.6 % ) compared to 42.1% ( 42.1 % ) and 37.1% ( 37.1 % ) for 2002 and 2001 . the higher rate in 2002 was due to the united kingdom enactment of a supplementary 10 percent tax on profits from the north sea oil and gas production , retroactively effective to april 17 , 2002 . in 2002 , marathon recognized a one-time noncash deferred tax adjustment of $ 61 million as a result of the rate increase . the following is an analysis of the effective tax rate for the periods presented: .

Table: 2003 2002 2001 statutory tax rate 35.0% ( 35.0 % ) 35.0% ( 35.0 % ) 35.0% ( 35.0 % ) effects of foreign operations ( a ) -0.4 ( 0.4 ) 5.6 -0.7 ( 0.7 ) state and local income taxes after federal income tax effects 2.2 3.9 3.0 other federal tax effects -0.2 ( 0.2 ) -2.4 ( 2.4 ) -0.2 ( 0.2 ) effective tax rate 36.6% ( 36.6 % ) 42.1% ( 42.1 % ) 37.1% ( 37.1 % )

( a ) the deferred tax effect related to the enactment of a supplemental tax in the u.k . increased the effective tax rate 7.0 percent in 2002. .

Question: by how much did the effective tax rate decrease from 2002 to 2003?
Answer: -5.5%
Calculation: subtract(36.6%, 42.1%)