Year	% of total fuel combustion
1971	2.678571428571428
1972	2.586206896551724
1973	3.937007874015748
1974	2.4000000000000004
1975	3.7593984962406015
1976	3.5211267605633805
1977	3.1645569620253164
1978	3.164556962025315
1979	3.571428571428571
1980	3.5294117647058822
1981	3.72670807453416
1982	3.7735849056603774
1983	3.40909090909091
1984	3.225806451612903
1985	4.790419161676647
1986	1.6326809185664068E-15
1987	0.5263157894736847
1988	0.4784688995215315
1989	0.4310344827586199
1990	1.2731915420013263E-15
1991	0.4629629629629647
1992	0.4065040650406508
1993	0.38461538461538386
1994	0.3333333333333327
1995	-7.774671040792413E-16
1996	0.5681818181818179
1997	0.27624309392265217
1998	0.23148148148148168
1999	5.963302752293577
2000	-6.181642676086617E-16
2001	13.232514177693764
2002	10.854092526690387
2003	12.980769230769232
2004	14.651493598862016
2005	14.245810055865919
2006	12.968750000000002
2007	2.339901477832512
2008	5.203045685279188
2009	7.027027027027027
2010	6.948228882833788
2011	3.579952267303103
2012	3.8323353293413174
2013	3.7869822485207107
2014	4.8