Year	% of total fuel combustion
1971	7.736389684813753
1972	7.670454545454544
1973	8.564231738035264
1974	7.648183556405354
1975	7.41989881956155
1976	7.142857142857142
1977	6.304079110012362
1978	5.735930735930736
1979	8.556701030927837
1980	9.03846153846154
1981	8.813559322033898
1982	7.529610829103214
1983	8.385933273219116
1984	10.37567084078712
1985	10.891938250428817
1986	10.747271200671703
1987	10.585197934595525
1988	9.113100081366966
1989	7.321131447587356
1990	1.5765765765765765
1991	1.0783608914450031
1992	0.9446693657219969
1993	1.1396011396011394
1994	1.006711409395974
1995	0.8987417615338533
1996	0.7291666666666663
1997	0.4894762604013694
1998	0.441176470588234
1999	0.36319612590798966
2000	1.1031439602868165
2001	3.371369294605809
2002	2.727272727272729
2003	2.9606942317508924
2004	7.5641602881584875
2005	7.943143812709029
2006	7.867820613690007
2007	9.773859716366427
2008	11.128107074569794
2009	11.81786583246437
2010	8.174726989079563
2011	8.830694275274054
2012	9.388710149166425
2013	7.750209088374685
2014	9.398399173767107