Year	% of total fuel combustion
1960	25.482738443534224
1961	23.872926886241526
1962	23.581152758132955
1963	22.876730273787164
1964	22.641430073606728
1965	22.09989806320081
1966	20.407354572832464
1967	19.076558498643116
1968	17.95433789954338
1969	19.42255434782609
1970	20.946686596910812
1971	16.274654911676695
1972	16.278970454559325
1973	15.829224251684144
1974	15.653894727346536
1975	15.965781409601638
1976	15.371783805801519
1977	15.298340062808435
1978	14.73949417749596
1979	14.632939407045473
1980	14.540605455651388
1981	15.012672263583086
1982	15.38265680094439
1983	15.028569509186656
1984	14.957382071659955
1985	15.95705179775976
1986	15.72193923808582
1987	15.700159091618056
1988	15.74068859213588
1989	14.973928224575678
1990	13.16632112416494
1991	12.889690305741617
1992	11.540536883376795
1993	11.727705504098472
1994	10.982881651216625
1995	10.580635725429016
1996	9.550004055478952
1997	10.176024542813083
1998	8.91876523151909
1999	9.461890271498797
2000	8.888044759937642
2001	8.73495913048538
2002	8.284326747102533
2003	7.934979170294561
2004	7.712866439816462
2005	7.276779008584257
2006	7.061938447672405
2007	6.7778197850206094
2008	6.736331227814137
2009	6.511891015873638
2010	6.261631164356234
2011	6.0201577563540765
2012	5.895387912141432
2013	5.891082135719044
2014	6.020293823757301