Year	% of total fuel combustion
1971	22.489082969432314
1972	23.69477911646586
1973	19.874804381846637
1974	23.42064714946071
1975	25.91943957968476
1976	23.42857142857143
1977	19.95661605206074
1978	19.13793103448276
1979	16.825396825396826
1980	24.360902255639097
1981	21.958925750394943
1982	9.401709401709404
1983	13.487475915221578
1984	18.165137614678898
1985	18.003025718608168
1986	20.254957507082153
1987	20.885200553250343
1988	16.087751371115175
1989	9.618874773139746
1990	9.618874773139746
1991	12.805755395683452
1992	10.144927536231883
1993	25.445544554455445
1994	27.436823104693143
1995	28.459734167318217
1996	22.2389181066867
1997	24.95075508864084
1998	10.154673839946202
1999	11.948881789137381
2000	11.865618298784845
2001	14.059405940594058
2002	11.788079470198676
2003	6.910299003322259
2004	12.837393021724818
2005	9.059474412171507
2006	5.929721815519766
2007	3.0807660283097418
2008	5.263157894736842
2009	16.242864556305136
2010	6.428571428571428
2011	3.6756756756756754
2012	12.238095238095237
2013	8.333333333333332
2014	13.500223513634332