a significant portion of our natural gas production in the lower 48 states of the u.s . is sold at bid-week prices or first-of-month indices relative to our specific producing areas . average settlement date henry hub natural gas prices have been relatively stable for the periods of this report ; however , a decline began in september 2011 which has continued in 2012 with february averaging $ 2.68 per mmbtu . should u.s . natural gas prices remain depressed , an impairment charge related to our natural gas assets may be necessary . our other major natural gas-producing regions are europe and eg . natural gas prices in europe have been significantly higher than in the u.s . in the case of eg our natural gas sales are subject to term contracts , making realized prices less volatile . the natural gas sales from eg are at fixed prices ; therefore , our worldwide reported average natural gas realized prices may not fully track market price movements . oil sands mining osm segment revenues correlate with prevailing market prices for the various qualities of synthetic crude oil we produce . roughly two-thirds of the normal output mix will track movements in wti and one-third will track movements in the canadian heavy sour crude oil marker , primarily western canadian select . output mix can be impacted by operational problems or planned unit outages at the mines or the upgrader . the operating cost structure of the oil sands mining operations is predominantly fixed and therefore many of the costs incurred in times of full operation continue during production downtime . per-unit costs are sensitive to production rates . key variable costs are natural gas and diesel fuel , which track commodity markets such as the canadian alberta energy company ( 201caeco 201d ) natural gas sales index and crude oil prices , respectively . recently aeco prices have declined , much as henry hub prices have . we would expect a significant , continued declined in natural gas prices to have a favorable impact on osm operating costs . the table below shows average benchmark prices that impact both our revenues and variable costs. .
how much has the western canadian select dollars per bbl increased since 2009?
wti crude oil ( dollars per bbl ) $ 95.11 $ 79.61 $ 62.09 western canadian select ( dollars per bbl ) ( a ) 77.97 65.31 52.13 aeco natural gas sales index ( dollars per mmbtu ) ( b ) $ 3.68 $ 3.89 $ 3.49 ( a ) monthly pricing based upon average wti adjusted for differentials unique to western canada . ( b ) monthly average day ahead index . integrated gas our integrated gas operations include production and marketing of products manufactured from natural gas , such as lng and methanol , in eg . world lng trade in 2011 has been estimated to be 241 mmt . long-term , lng continues to be in demand as markets seek the benefits of clean burning natural gas . market prices for lng are not reported or posted . in general , lng delivered to the u.s . is tied to henry hub prices and will track with changes in u.s . natural gas prices , while lng sold in europe and asia is indexed to crude oil prices and will track the movement of those prices . we have a 60 percent ownership in an lng production facility in equatorial guinea , which sells lng under a long-term contract at prices tied to henry hub natural gas prices . gross sales from the plant were 4.1 mmt , 3.7 mmt and 3.9 mmt in 2011 , 2010 and 2009 . we own a 45 percent interest in a methanol plant located in equatorial guinea through our investment in ampco . gross sales of methanol from the plant totaled 1039657 , 850605 and 960374 metric tonnes in 2011 , 2010 and 2009 . methanol demand has a direct impact on ampco 2019s earnings . because global demand for methanol is rather limited , changes in the supply-demand balance can have a significant impact on sales prices . world demand for methanol in 2011 has been estimated to be 55.4 mmt . our plant capacity of 1.1 mmt is about 2 percent of total demand . operating and financial highlights significant operating and financial highlights during 2011 include : 2022 completed the spin-off of our downstream business on june 30 , 2011 2022 acquired a significant operated position in the eagle ford shale play in south texas 2022 added net proved reserves , for the e&p and osm segments combined , of 307 mmboe , excluding dispositions , for a 212 percent reserve replacement ratio .