Year	% of total fuel combustion
1960	0.032883919763235896
1961	0.03262642740619984
1962	-1.9118845138049268E-15
1963	0.027122321670732707
1964	0.026539278131636704
1965	0.02720348204569895
1966	0.02699784017278867
1967	0.02646903123345986
1968	0.024709661477640046
1969	0.02328288707799569
1970	0.08609556607834931
1971	0.061728395061727365
1972	0.07936507936507955
1973	0.055762081784385534
1974	0.039123630672924965
1975	0.040420371867421215
1976	0.03707823507600877
1977	0.03897116134061015
1978	0.05591798695247101
1979	0.05366726296958423
1980	4.766286345233714
1981	4.907856450048496
1982	4.942736588306208
1983	4.575825065802791
1984	4.729199372056513
1985	4.38829787234043
1986	4.048034088708115
1987	3.837342497136313
1988	3.636002384263859
1989	3.3743549027391815
1990	2.203269367448474
1991	1.9851116625310166
1992	2.104695089044792
1993	1.8817204301075265
1994	1.760939167556031
1995	1.7116965933881523
1996	1.6269151792765753
1997	1.6477363621820507
1998	1.6473942658007292
1999	1.7238575378110261
2000	1.6486180701470812
2001	1.524758454106282
2002	1.4359733530717982
2003	1.358770244304144
2004	1.311519740400215
2005	1.1938296445338705
2006	1.1686143572621022
2007	1.1801957397812304
2008	1.1776533103547306
2009	1.2091708542713568
2010	1.1067423911460599
2011	1.1081162024558242
2012	1.1580594679186222
2013	1.1365405573719451
2014	1.184600197433365