Year	% of total fuel combustion
1960	1.598029969611234
1961	1.6171965245341793
1962	1.463761250592139
1963	1.5555451436068024
1964	1.5519263737255262
1965	1.5376573594110727
1966	1.5351250212621192
1967	1.484130899523106
1968	1.5337302369593484
1969	1.6003507618108082
1970	1.7453688831780705
1971	1.8582315481783067
1972	1.9126139056710831
1973	1.9469309462915598
1974	1.860221996740768
1975	1.9267652179044554
1976	1.933846450936579
1977	1.975683890577507
1978	1.8567108978684077
1979	1.9673503557974044
1980	2.1105261892742986
1981	2.1124387651953036
1982	1.975245629705244
1983	1.9281999238868446
1984	1.752330746326939
1985	2.007385664236342
1986	2.118020689816221
1987	1.84797061276001
1988	2.0496349015620696
1989	1.9537672889060858
1990	2.325783719513962
1991	2.806895954257991
1992	3.1665236305525166
1993	3.7380144564094997
1994	4.117770641375791
1995	3.9770852703878097
1996	3.9950741737785664
1997	4.299325363948396
1998	4.215921832452347
1999	4.4771684220952865
2000	4.360284471449286
2001	4.298430951473796
2002	4.1001874977889425
2003	4.0211459754433845
2004	4.066026612767392
2005	4.250438537309406
2006	3.493124026984952
2007	3.1839237946108163
2008	3.3839321224976793
2009	3.422613944236772
2010	3.3844853371480603
2011	3.2682540729503344
2012	3.4087460804477567
2013	3.3689400164338545
2014	3.390194954128441