Year	% of total fuel combustion
1971	13.30275229357798
1972	12.916666666666668
1973	13.83399209486166
1974	14.5985401459854
1975	13.354037267080745
1976	13.314447592067987
1977	13.333333333333334
1978	13.022113022113022
1979	13.267813267813267
1980	14.014251781472684
1981	12.803532008830022
1982	12.525667351129362
1983	11.943319838056679
1984	12.854030501089325
1985	14.153132250580047
1986	14.457831325301203
1987	14.712643678160923
1988	13.615023474178404
1989	12.5
1990	11.067961165048542
1991	10.638297872340427
1992	11.090573012939
1993	11.190053285968029
1994	11.147540983606559
1995	10.595065312046446
1996	12.5193199381762
1997	14.48382126348228
1998	13.832853025936597
1999	14.525993883792049
2000	11.549295774647888
2001	12.62848751835536
2002	12.727272727272727
2003	12.27621483375959
2004	12.206572769953054
2005	12.127894156560089
2006	11.448834853090174
2007	10.936051899907325
2008	10.051107325383306
2009	9.516129032258066
2010	9.27007299270073
2011	9.011432414256895
2012	8.248655110579797
2013	8.456534594914253
2014	8.251366120218579