Please answer the given financial question based on the context.
Context: for additional information on segment results see page 43 . income from equity method investments increased by $ 126 million in 2006 from 2005 and increased by $ 98 million in 2005 from 2004 . income from our lpg operations in equatorial guinea increased in both periods due to higher sales volumes as a result of the plant expansions completed in 2005 . the increase in 2005 also included higher ptc income as a result of higher distillate gross margins . cost of revenues increased $ 4.609 billion in 2006 from 2005 and $ 7.106 billion in 2005 from 2004 . in both periods the increases were primarily in the rm&t segment and resulted from increases in acquisition costs of crude oil , refinery charge and blend stocks and purchased refined products . the increase in both periods was also impacted by higher manufacturing expenses , primarily the result of higher contract services and labor costs in 2006 and higher purchased energy costs in 2005 . purchases related to matching buy/sell transactions decreased $ 6.968 billion in 2006 from 2005 and increased $ 3.314 billion in 2005 from 2004 , mostly in the rm&t segment . the decrease in 2006 was primarily related to the change in accounting for matching buy/sell transactions discussed above . the increase in 2005 was primarily due to increased crude oil prices . depreciation , depletion and amortization increased $ 215 million in 2006 from 2005 and $ 125 million in 2005 from 2004 . rm&t segment depreciation expense increased in both years as a result of the increase in asset value recorded for our acquisition of the 38 percent interest in mpc on june 30 , 2005 . in addition , the detroit refinery expansion completed in the fourth quarter of 2005 contributed to the rm&t depreciation expense increase in 2006 . e&p segment depreciation expense for 2006 included a $ 20 million impairment of capitalized costs related to the camden hills field in the gulf of mexico and the associated canyon express pipeline . natural gas production from the camden hills field ended in 2006 as a result of increased water production from the well . selling , general and administrative expenses increased $ 73 million in 2006 from 2005 and $ 134 million in 2005 from 2004 . the 2006 increase was primarily because personnel and staffing costs increased throughout the year primarily as a result of variable compensation arrangements and increased business activity . partially offsetting these increases were reductions in stock-based compensation expense . the increase in 2005 was primarily a result of increased stock-based compensation expense , due to the increase in our stock price during that year as well as an increase in equity-based awards , which was partially offset by a decrease in expense as a result of severance and pension plan curtailment charges and start-up costs related to egholdings in 2004 . exploration expenses increased $ 148 million in 2006 from 2005 and $ 59 million in 2005 from 2004 . exploration expense related to dry wells and other write-offs totaled $ 166 million , $ 111 million and $ 47 million in 2006 , 2005 and 2004 . exploration expense in 2006 also included $ 47 million for exiting the cortland and empire leases in nova scotia . net interest and other financing costs ( income ) reflected a net $ 37 million of income for 2006 , a favorable change of $ 183 million from the net $ 146 million expense in 2005 . net interest and other financing costs decreased $ 16 million in 2005 from 2004 . the favorable changes in 2006 included increased interest income due to higher interest rates and average cash balances , foreign currency exchange gains , adjustments to interest on tax issues and greater capitalized interest . the decrease in expense for 2005 was primarily a result of increased interest income on higher average cash balances and greater capitalized interest , partially offset by increased interest on potential tax deficiencies and higher foreign exchange losses . included in net interest and other financing costs ( income ) are foreign currency gains of $ 16 million , losses of $ 17 million and gains of $ 9 million for 2006 , 2005 and 2004 . minority interest in income of mpc decreased $ 148 million in 2005 from 2004 due to our acquisition of the 38 percent interest in mpc on june 30 , 2005 . provision for income taxes increased $ 2.308 billion in 2006 from 2005 and $ 979 million in 2005 from 2004 , primarily due to the $ 4.259 billion and $ 2.691 billion increases in income from continuing operations before income taxes . the increase in our effective income tax rate in 2006 was primarily a result of the income taxes related to our libyan operations , where the statutory income tax rate is in excess of 90 percent . the following is an analysis of the effective income tax rates for continuing operations for 2006 , 2005 and 2004 . see note 11 to the consolidated financial statements for further discussion. .
||2006|2005|2004|
|statutory u.s . income tax rate|35.0% ( 35.0 % )|35.0% ( 35.0 % )|35.0% ( 35.0 % )|
|effects of foreign operations including foreign tax credits|9.9|-0.8 ( 0.8 )|0.5|
|state and local income taxes net of federal income tax effects|1.9|2.5|1.6|
|other tax effects|-2.0 ( 2.0 )|-0.4 ( 0.4 )|-0.9 ( 0.9 )|
|effective income tax rate for continuing operations|44.8% ( 44.8 % )|36.3% ( 36.3 % )|36.2% ( 36.2 % )|
.
Question: by what percentage did effects of foreign operations including foreign tax credits increase from 2004 to 2006?
Answer:
18.8