Year	% of total fuel combustion
1971	17.473118279569892
1972	15.740740740740739
1973	13.84083044982699
1974	14.15929203539823
1975	12.456747404844291
1976	15.29284164859002
1977	14.995313964386131
1978	16.526845637583893
1979	17.834890965732086
1980	12.969283276450513
1981	13.931718061674008
1982	14.467005076142133
1983	12.131630648330061
1984	11.715481171548117
1985	11.064030131826744
1986	9.670131043831903
1987	9.146877748460863
1988	7.308306709265176
1989	7.3963391856555845
1990	8.052651955090981
1991	8.57365549493375
1992	9.445100354191263
1993	7.6001497566454495
1994	7.615681233933162
1995	8.318154219793565
1996	7.816556100374964
1997	9.006660874601796
1998	8.486562942008486
1999	8.866995073891626
2000	8.705114254624593
2001	8.708311275807306
2002	7.987942727957799
2003	7.612623464225489
2004	8.606460740391418
2005	7.933922754769661
2006	7.108664432742939
2007	7.246003094378546
2008	8.831230659366817
2009	8.4108012394865
2010	7.346514047866805
2011	3.695082921152168
2012	3.0296179063983724
2013	5.789582901016809
2014	4.133611691022965