Year	% of total fuel combustion
1971	3.81679389312977
1972	3.3057851239669414
1973	3.0769230769230775
1974	3.787878787878788
1975	4.23728813559322
1976	4.237288135593221
1977	4.273504273504274
1978	4.8
1979	5.303030303030303
1980	5.925925925925926
1981	5.369127516778525
1982	7.4074074074074066
1983	8.965517241379311
1984	7.4074074074074066
1985	5.755395683453238
1986	9.756097560975613
1987	13.978494623655912
1988	10.362694300518136
1989	9.852216748768477
1990	12.442396313364057
1991	12.217194570135748
1992	7.194244604316549
1993	6.111111111111112
1994	5.797101449275364
1995	6.0344827586206895
1996	6.563706563706563
1997	6.545454545454545
1998	7.191780821917808
1999	7.534246575342466
2000	7.500000000000001
2001	7.425742574257428
2002	7.600950118764849
2003	7.439824945295402
2004	7.916666666666668
2005	8.017817371937637
2006	8.124999999999998
2007	7.977736549165123
2008	7.66609880749574
2009	7.512520868113522
2010	7.885906040268457
2011	7.278020378457062
2012	7.8404401650619
2013	7.882352941176469
2014	7.886089813800656