Year	% of total fuel combustion
1960	13.599570899161302
1961	13.211866386358327
1962	13.12323196605375
1963	13.274529496528535
1964	12.64353312302839
1965	11.971457696228338
1966	11.852116024726582
1967	11.585062875052552
1968	11.404566210045662
1969	10.740489130434783
1970	10.59292476332835
1971	11.140641590784778
1972	11.428344833055752
1973	11.835891381345926
1974	12.03317396599161
1975	11.628192032686414
1976	11.443008020482782
1977	10.816465226603414
1978	10.464434104041597
1979	10.562367765841797
1980	10.461344105307484
1981	10.618168857912243
1982	10.587391113134322
1983	10.421619523555384
1984	10.018902263352796
1985	10.16014467341901
1986	10.330184791388493
1987	10.12883301618991
1988	10.05409731588386
1989	10.466863987420801
1990	11.35255207819133
1991	11.348487298468434
1992	11.62757286548848
1993	11.264341329913623
1994	10.917933524484253
1995	10.760042901716067
1996	11.876064563224917
1997	11.636859450769341
1998	11.985215272136472
1999	12.430981506746736
2000	13.256570356829133
2001	13.243621507562922
2002	13.268248868824765
2003	12.92486571202765
2004	12.99071744515323
2005	12.39762896004699
2006	12.082748342337595
2007	11.971184985243736
2008	12.364319430825716
2009	12.104801605163662
2010	12.016703403056685
2011	11.845350968050358
2012	12.300576726999655
2013	12.59396592747692
2014	12.87931512893644