Year	% of total fuel combustion
1960	26.435489912773587
1961	26.298463789319676
1962	25.29855129209084
1963	24.29618025157812
1964	24.837501614222376
1965	25.053036064523877
1966	24.906036664876886
1967	24.411274545322804
1968	23.509967281681114
1969	23.182641314189624
1970	23.65432693755836
1971	22.83992356313391
1972	22.303887320794793
1973	25.771493995793065
1974	26.026579452837044
1975	24.093573455693186
1976	23.341213958986483
1977	23.6252241482367
1978	22.392318380309646
1979	22.846459901251134
1980	22.80834734822465
1981	21.778539323052474
1982	19.85009984698774
1983	19.39467504024065
1984	19.79203652041593
1985	19.532261750590386
1986	19.920659614187926
1987	19.98739124952717
1988	19.258807810412318
1989	18.66476694484022
1990	18.201754385964914
1991	17.99273607748184
1992	17.23311802701116
1993	17.310964083175804
1994	17.431569343065696
1995	17.27295003452808
1996	17.520850438615447
1997	16.936292952094306
1998	16.16178291374329
1999	15.98035053672145
2000	15.996667764496191
2001	15.060276504946016
2002	15.137552250413142
2003	15.203309869701961
2004	15.837594327966695
2005	13.655901921208041
2006	13.90521254674502
2007	13.424061556162808
2008	12.299898682877405
2009	11.392528276909301
2010	11.659218408291338
2011	12.349065935091353
2012	12.550260610573345
2013	12.005385049211345
2014	12.04397981254506