Year	% of total fuel combustion
1960	26.857517482517483
1961	27.686784832847206
1962	29.934557736964322
1963	29.938861291555213
1964	28.64630399421652
1965	28.805073431241652
1966	28.235472614170842
1967	27.78927264045838
1968	27.310090702947843
1969	26.395809377794816
1970	32.19440685611186
1971	33.46744696415509
1972	33.62551740930119
1973	33.25751227104034
1974	29.36715481171548
1975	33.109732945196804
1976	32.42833838266139
1977	31.374441896947026
1978	30.934880722114766
1979	30.098663669289373
1980	28.78642769188671
1981	30.618104881366182
1982	27.55540853456831
1983	25.49590536851683
1984	21.95483154387264
1985	20.54137399348981
1986	21.59090909090909
1987	19.96207550422341
1988	19.413458078445483
1989	17.870001895016106
1990	17.652708413369187
1991	16.63526752072344
1992	16.229331416247305
1993	15.379061371841155
1994	15.603207810320779
1995	15.495432185523542
1996	15.416666666666668
1997	15.286171347316035
1998	14.001048767697954
1999	14.09730885760114
2000	12.064652684240908
2001	12.179863147605085
2002	11.018395600227576
2003	10.781771026306041
2004	8.338114362210748
2005	7.251986147891627
2006	4.7200171636987776
2007	4.491883477874138
2008	3.982300884955752
2009	5.502333578973226
2010	5.516941789748046
2011	5.162659123055162
2012	4.067107269954245
2013	3.5847052575677107
2014	4.008551576696953