Year	% of total fuel combustion
1971	17.719680464778502
1972	17.186417186417184
1973	18.274760383386578
1974	17.25663716814159
1975	17.73308957952468
1976	17.53640776699029
1977	16.513233601841197
1978	16.953713670613563
1979	16.315789473684212
1980	15.649867374005305
1981	15.835030549898166
1982	15.671285236502627
1983	14.370982552800735
1984	14.380238200264664
1985	14.027149321266968
1986	13.398203592814372
1987	13.038978958261469
1988	12.349299446073639
1989	11.424100156494523
1990	9.692167022249313
1991	9.453781512605042
1992	4.585091420534459
1993	6.019467213114754
1994	6.3560334528076465
1995	6.529975484733676
1996	5.972369819341127
1997	3.8789601949634442
1998	3.40701683228554
1999	3.037475345167653
2000	2.681014043406894
2001	2.3342836778332146
2002	2.1772151898734178
2003	1.6724053123462863
2004	1.4386136995259113
2005	1.3947950331689063
2006	1.435483870967742
2007	1.5250544662309367
2008	2.621374282612068
2009	3.164160401002506
2010	4.413269034049393
2011	1.2592592592592593
2012	1.7765120694331438
2013	3.7688442211055273
2014	4.482918534549389