Year	% of total fuel combustion
1960	17.763799492880825
1961	18.03316982013548
1962	18.803041018387553
1963	18.697873455307626
1964	18.641430073606728
1965	19.13557594291539
1966	19.543509272467904
1967	19.93272942705347
1968	19.134246575342466
1969	18.4375
1970	18.000332170735756
1971	39.308858071366515
1972	38.722036152442996
1973	37.993957913744005
1974	38.36035812547923
1975	39.24004085801839
1976	39.82019377176052
1977	40.8210403812925
1978	39.79153104933658
1979	38.77076295456406
1980	38.08584306814106
1981	36.91232377633456
1982	36.93550502673466
1983	37.049297798412354
1984	37.73355538222626
1985	34.96159690849956
1986	34.794850238201214
1987	34.65857690987928
1988	34.27724503860918
1989	33.73144337048513
1990	24.576957251456214
1991	24.229847660020674
1992	24.076224141877006
1993	24.395831559191226
1994	25.043895387489727
1995	27.663481539261568
1996	25.66177305539784
1997	25.466773954070717
1998	25.608448415922005
1999	23.36170051692897
2000	23.16785767985882
2001	23.398677597870922
2002	22.999070990693763
2003	22.81957858358003
2004	25.371466196606477
2005	26.53318357400196
2006	26.070390418393888
2007	27.23886392877134
2008	28.132814934744115
2009	28.634054557298587
2010	28.201878832546413
2011	28.080312325711102
2012	27.393275655396586
2013	26.797449319501286
2014	27.22706672064606