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: .
by how much did the effective tax rate decrease from 2002 to 2004?
( 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 .