Year	% of total fuel combustion
1971	21.26408134782175
1972	20.566234258119497
1973	22.066756574511125
1974	22.08333333333333
1975	22.171525790735448
1976	23.20073095305032
1977	23.390328613411697
1978	21.217476083114985
1979	23.406113537117903
1980	20.400972656443848
1981	19.73448325984786
1982	20.237818756096427
1983	18.515403682719544
1984	18.594735697193826
1985	19.123489138703405
1986	17.795288516785686
1987	18.018412976764576
1988	17.369024856596557
1989	17.05784043017003
1990	19.794300160882557
1991	20.46620180948539
1992	16.82232537330127
1993	16.3695430381786
1994	15.870464546388765
1995	16.673479816044967
1996	15.784139226737864
1997	14.969811494676682
1998	15.842719027210206
1999	16.638802643101663
2000	15.54708630440128
2001	14.923692194538935
2002	15.274991352473194
2003	16.070777919475315
2004	15.574639056912007
2005	14.976206803399624
2006	14.751767028208775
2007	12.562835941070222
2008	15.897256547757832
2009	14.204114164262943
2010	16.606165778336553
2011	16.823496915569475
2012	16.476873812010894
2013	16.02509461625013
2014	14.668790877075299