Year	% of total fuel combustion
1960	33.10810810810811
1961	31.208997188378635
1962	31.741293532338304
1963	29.74217311233886
1964	30.11314186248912
1965	29.770992366412212
1966	27.973748974569325
1967	29.28452579034942
1968	26.98933552091879
1969	25.15479876160991
1970	32.08092485549133
1971	33.03703703703704
1972	32.44990303813833
1973	30.778443113772454
1974	29.844738355376656
1975	28.058429701765064
1976	25.852585258525856
1977	25.106837606837612
1978	24.601867105985722
1979	26.955990220048903
1980	28.96174863387978
1981	27.93846153846154
1982	25.64102564102564
1983	24.197120708748617
1984	25
1985	24.444444444444446
1986	25.39149888143177
1987	25.66649242028228
1988	29.05438510534052
1989	26.69264490988797
1990	27.23091076356946
1991	27.425203989120583
1992	25.3781512605042
1993	26.85738684884714
1994	26.433389544688023
1995	25.03134141245299
1996	24.33841218925421
1997	21.486387049300955
1998	20.965930363159863
1999	19.60156527926005
2000	20.780117362789092
2001	20.628809752967594
2002	21.589446589446588
2003	18.956627236882014
2004	17.97718162195498
2005	14.866468842729969
2006	15.017772511848342
2007	16.77399570683839
2008	16.502242152466366
2009	16.841759684832567
2010	17.85831960461285
2011	16.964586846543003
2012	16.533162447933357
2013	19.186046511627907
2014	21.734955185659413