gain or loss on ownership change in map results from contributions to map of certain environmental capital expenditures and leased property acquisitions funded by marathon and ashland .in accordance with map 2019s limited liability company agreement , in certain instances , environmental capital 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 $ 5.822 billion in 2004 from 2003 and by $ 6.040 billion in 2003 from 2002 .the increases are primarily in the rm&t segment and result from higher acquisition costs for crude oil , refined products , refinery charge and blend feedstocks and increased manufacturing expenses .selling , general and administrative expenses increased by $ 105 million in 2004 from 2003 and by $ 97 million in 2003 from 2002 .the increase in 2004 was primarily due to increased stock-based compensation and higher costs associated with business transformation and outsourcing .our 2004 results were also impacted by start-up costs associated with the lng project in equatorial guinea and the increased cost of complying with governmental regulations .the increase in 2003 was primarily due to increased employee benefit expenses ( 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 .additionally , during 2003 , we recorded a charge of $ 24 million related to organizational and business process changes .inventory market valuation reserve ( 2018 2018imv 2019 2019 ) is established to reduce the cost basis of inventories to current market value .generally , we will establish an imv reserve when crude oil prices fall below $ 22 per barrel .the 2002 results of operations include credits to income from operations of $ 71 million , reversing the imv reserve at december 31 , 2001 .net interest and other financial costs decreased by $ 25 million in 2004 from 2003 and by $ 82 million in 2003 from 2002 .the decrease in 2004 is primarily due to an increase in interest income .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 a reduction in interest on tax deficiencies and increased interest income on investments .additionally , included in net interest and other financing costs are foreign currency gains of $ 9 million , $ 13 million and $ 8 million for 2004 , 2003 and 2002 .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 .minority interest in income of map , which represents ashland 2019s 38 percent ownership interest , increased by $ 230 million in 2004 from 2003 and by $ 129 million in 2003 from 2002 .map income was higher in 2004 compared to 2003 and in 2003 compared to 2002 as discussed below in the rm&t segment .minority interest in loss of equatorial guinea lng holdings limited , which represents gepetrol 2019s 25 percent ownership interest , was $ 7 million in 2004 , primarily resulting from gepetrol 2019s share of start-up costs associated with the lng project in equatorial guinea .provision for income taxes increased by $ 143 million in 2004 from 2003 and by $ 215 million in 2003 from 2002 , primarily due to $ 388 million and $ 720 million increases in income before income taxes .the effective tax rate for 2004 was 36.6 percent compared to 36.6 percent and 42.1 percent for 2003 and 2002 .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 , we 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: .
[['', '2004', '2003', '2002'], ['statutory tax rate', '35.0% ( 35.0 % )', '35.0% ( 35.0 % )', '35.0% ( 35.0 % )'], ['effects of foreign operations ( a )', '1.3', '-0.4 ( 0.4 )', '5.6'], ['state and local income taxes after federal income tax effects', '1.6', '2.2', '3.9'], ['other federal tax effects', '-1.3 ( 1.3 )', '-0.2 ( 0.2 )', '-2.4 ( 2.4 )'], ['effective tax rate', '36.6% ( 36.6 % )', '36.6% ( 36.6 % )', '42.1% ( 42.1 % )']]
( 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 .

Question: by how much did the effective tax rate decrease from 2002 to 2004?
Answer: -5.50%