Year	% of total fuel combustion
1960	13.132123936426392
1961	14.128958093844707
1962	15.994518402505872
1963	17.26028659632309
1964	17.98889415005811
1965	19.221070327822922
1966	19.73613561402163
1967	20.545612636765455
1968	22.04944851081054
1969	22.199586082007503
1970	22.2145245338715
1971	23.39850066147288
1972	22.91311516641981
1973	22.869238757089224
1974	21.499766391527803
1975	23.215659231360902
1976	23.289818574292028
1977	24.681211396692568
1978	25.06202858277094
1979	24.48827956473803
1980	25.342871355141295
1981	25.58543792992128
1982	28.06608055188154
1983	29.75433411615695
1984	31.02713669794573
1985	30.573119016784737
1986	29.926363824932583
1987	31.60509393519102
1988	32.90593281920255
1989	33.459981455096454
1990	32.901887871853546
1991	33.58595641646489
1992	34.22665883734586
1993	32.46691871455577
1994	32.38138686131387
1995	32.817268494798505
1996	32.105354133356386
1997	33.6970152997241
1998	36.22988031366075
1999	35.819839488952226
2000	36.61971830985916
2001	38.19740801195697
2002	37.64168367842909
2003	38.050396884828515
2004	36.486152559448
2005	37.72893772893772
2006	37.66313058078302
2007	38.74406730907522
2008	39.63341622916091
2009	39.54873751630424
2010	39.870685556717696
2011	38.82014818132616
2012	39.30752047654505
2013	39.35088325722707
2014	38.72927180966114