key operating and financial activities significant operating and financial activities during 2012 include : 2022 net proved reserve additions for the e&p and osm segments combined of 389 mmboe , for a 226 percent reserve replacement 2022 increased proved liquid hydrocarbon and synthetic crude oil reserves by 316 mmbbls , for a reserve replacement of 268 percent for these commodities 2022 recorded more than 95 percent average operational availability for operated e&p assets 2022 increased e&p net sales volumes , excluding libya , by 8 percent 2022 eagle ford shale average net sales volumes of 65 mboed for december 2012 , a fourfold increase over december 2011 2022 bakken shale average net sales volumes of 29 mboed , a 71 percent increase over last year 2022 resumed sales from libya and reached pre-conflict production levels 2022 international liquid hydrocarbon sales volumes , for which average realizations have exceeded wti , were 62 percent of net e&p liquid hydrocarbon sales 2022 closed $ 1 billion of acquisitions in the core of the eagle ford shale 2022 assumed operatorship of the vilje field located offshore norway 2022 signed agreements for new exploration positions in e.g. , gabon , kenya and ethiopia 2022 issued $ 1 billion of 3-year senior notes at 0.9 percent interest and $ 1 billion of 10-year senior notes at 2.8 percent interest some significant 2013 activities through february 22 , 2013 include : 2022 closed sale of our alaska assets in january 2013 2022 closed sale of our interest in the neptune gas plant in february 2013 consolidated results of operations : 2012 compared to 2011 consolidated income before income taxes was 38 percent higher in 2012 than consolidated income from continuing operations before income taxes were in 2011 , largely due to higher liquid hydrocarbon sales volumes in our e&p segment , partially offset by lower earnings from our osm and ig segments . the 7 percent decrease in income from continuing operations included lower earnings in the u.k . and e.g. , partially offset by higher earnings in libya . also , in 2011 we were not in an excess foreign tax credit position for the entire year as we were in 2012 . the effective income tax rate for continuing operations was 74 percent in 2012 compared to 61 percent in 2011 . revenues are summarized in the following table: .
what percentage of total revenues consited of e&p production in 2012?
e&p segment revenues increased $ 1055 million from 2011 to 2012 , primarily due to higher average liquid hydrocarbon sales volumes . e&p segment revenues included a net realized gain on crude oil derivative instruments of $ 15 million in 2012 while the impact of derivatives was not significant in 2011 . see item 8 . financial statements and supplementary data 2013 note 16 to the consolidated financial statement for more information about our crude oil derivative instruments . included in our e&p segment are supply optimization activities which include the purchase of commodities from third parties for resale . see the cost of revenues discussion as revenues from supply optimization approximate the related costs . supply optimization serves to aggregate volumes in order to satisfy transportation commitments and to achieve flexibility within product .