Year	% of total fuel combustion
1971	7.8588873812754425
1972	7.653675124247972
1973	6.995943688857075
1974	6.777618098372816
1975	6.642146257031588
1976	6.469680980599075
1977	5.740846448666721
1978	6.875559534467324
1979	6.277494281189511
1980	5.3370669118568985
1981	4.46090731668459
1982	4.175144461626109
1983	4.127037331880839
1984	4.961573686935052
1985	4.924744599547688
1986	4.3847962382445145
1987	4.155104425295749
1988	4.61124445414212
1989	5.1531983515499
1990	5.1756326925736404
1991	5.331882480957565
1992	5.3504224952069865
1993	6.305459860110659
1994	5.8980226085174685
1995	5.327653997378769
1996	4.92271558701241
1997	4.855368771770408
1998	4.5661425700437395
1999	4.564942475555967
2000	4.32373512580616
2001	4.838972465106175
2002	5.4715489989462585
2003	5.6737942563437205
2004	5.750457949776242
2005	6.107100577981012
2006	6.89387540803981
2007	7.990404536037509
2008	8.016869082135399
2009	8.302372709617496
2010	4.566228846708116
2011	5.079060852898898
2012	6.374558019929284
2013	6.3937195285807515
2014	6.218841168433102