Year	% of total fuel combustion
1960	0.6896551724137919
1961	0.797679477882526
1962	0.7194244604316521
1963	0.6289308176100619
1964	0.540540540540541
1965	0.4201680672268943
1966	0.5732484076433112
1967	0.41249263406010483
1968	0.4294149221685448
1969	0.41279669762641663
1970	0.3067484662576687
1971	0.2772643253234779
1972	0.28050490883590334
1973	0.3362151777137368
1974	0.30987162461266077
1975	0.23651844843897793
1976	0.22862368541380754
1977	0.255536626916524
1978	0.5603448275862055
1979	0.48076923076922956
1980	0.30899961375048224
1981	0.2724795640326961
1982	0.1978630787495073
1983	0.1592356687898126
1984	0.36144578313253134
1985	0.26465028355387377
1986	2.4034959941733467
1987	2.0962199312714773
1988	2.170818505338075
1989	2.086897023605884
1990	2.1919628030554605
1991	2.2135416666666643
1992	2.238079792409993
1993	2.2587931590835746
1994	2.434456928838952
1995	2.788844621513947
1996	2.118893466745145
1997	2.143469562732208
1998	2.0212765957446788
1999	2.020460358056266
2000	2.00832721038452
2001	1.9320297951582859
2002	1.9486692015209122
2003	1.9776030497974735
2004	1.8876828692779586
2005	1.9213381555153688
2006	1.7916390179163921
2007	1.7322834645669292
2008	1.7711171662125356
2009	1.7477203647416402
2010	1.7798118484617358
2011	1.8171493469619513
2012	1.6811431773606031
2013	1.6564952048823018
2014	1.5652687536916732