Year	% of total fuel combustion
1960	18.989071038251364
1961	17.93020457280385
1962	18.59688195991091
1963	18.69158878504673
1964	15.627743634767338
1965	13.882352941176471
1966	10.118632240055826
1967	10.964083175803403
1968	10.80607476635514
1969	11.556480999479438
1970	12.791783380018673
1971	12.609736632083003
1972	11.817553559087767
1973	11.476868327402135
1974	10.849349039057657
1975	10.733137829912023
1976	9.605974761782129
1977	8.308457711442784
1978	10.196905766526019
1979	8.33147694364001
1980	7.14759902633326
1981	6.962167002462502
1982	8.550913838120104
1983	6.8158697863682605
1984	6.725663716814159
1985	6.842781141075033
1986	6.399411548363368
1987	7.385129490392647
1988	7.06342991386061
1989	7.819767441860466
1990	7.381974248927039
1991	7.569493941553813
1992	7.144831398562741
1993	7.071685579850538
1994	6.985244348179235
1995	7.08218999085326
1996	9.498887871254743
1997	9.728682170542633
1998	9.753682386433963
1999	9.484459792797239
2000	9.42259604455558
2001	10.099889012208656
2002	10.416205446092539
2003	11.810436634717785
2004	11.481719050673506
2005	11.889507404684382
2006	11.757833244822093
2007	10.310330747243773
2008	10.497881355932202
2009	9.588737390533202
2010	9.338288180292496
2011	12.048192771084338
2012	9.683281412253374
2013	6.459573232689795
2014	6.663630843958712