Year	% of total fuel combustion
1971	26.77165354330709
1972	23.23943661971831
1973	25.766871165644172
1974	19.62025316455696
1975	21.839080459770116
1976	20.555555555555554
1977	22.80701754385965
1978	22.54098360655738
1979	21.810699588477366
1980	25.925925925925924
1981	31.18811881188119
1982	22.61904761904762
1983	24.85549132947977
1984	25.543478260869563
1985	28.717948717948723
1986	24.75728155339806
1987	23.636363636363637
1988	18.18181818181818
1989	23.954372623574148
1990	26.153846153846157
1991	23.55072463768116
1992	14.248704663212436
1993	14.96062992125984
1994	14.606741573033707
1995	15.090090090090088
1996	15.587529976019185
1997	17.11491442542787
1998	16.703296703296704
1999	17.54385964912281
2000	19.11111111111111
2001	18.329938900203665
2002	14.54183266932271
2003	18.045112781954884
2004	17.51412429378531
2005	17.64705882352941
2006	16.582914572864322
2007	18.140929535232384
2008	17.514970059880238
2009	16.19496855345912
2010	15.582450832072617
2011	14.940828402366865
2012	15.350877192982457
2013	14.165497896213184
2014	13.668061366806135