Year	% of total fuel combustion
1960	2.8544776119402986
1961	3.0282055718982512
1962	3.0817402768622277
1963	3.4554805528768875
1964	3.5465202552307473
1965	3.37799315849487
1966	5.165858135570998
1967	4.735142891306948
1968	4.726688102893892
1969	4.7671397161702975
1970	4.582531390340024
1971	4.301075268817205
1972	4.473789515806322
1973	4.449867221703869
1974	3.3876955714664545
1975	3.1839774040313267
1976	2.9515801681646856
1977	3.69944296439816
1978	4.08063828491382
1979	4.035258428252534
1980	3.5553168635875405
1981	3.2176656151419554
1982	3.621774018651052
1983	3.586632609621115
1984	3.821834256616865
1985	4.138728323699422
1986	3.930746672682158
1987	4.093206064008983
1988	3.5688675602625617
1989	2.0031204388746287
1990	2.0779861796643635
1991	2.177116509007938
1992	2.226228030644435
1993	2.4551962715610443
1994	2.4572403300908214
1995	2.388569925932419
1996	2.4915114251628885
1997	2.273016411517747
1998	1.9970292127413765
1999	2.088545220225912
2000	2.322909560909058
2001	2.123552123552123
2002	1.9888275676403278
2003	2.5714757891257647
2004	2.7850877192982453
2005	2.47579654107844
2006	3.215780403741998
2007	2.6496536206998647
2008	2.499273467015402
2009	2.7028006231658277
2010	3.1147415833269716
2011	2.809667673716011
2012	2.9258178467209337
2013	3.471011102131101
2014	3.301866459761196