Year	% of total fuel combustion
1990	53.92583565459611
1991	53.5202964460165
1992	50.60273479668946
1993	52.567760342368054
1994	55.08036469593007
1995	9.339961920880048
1996	5.87743149968626
1997	5.333746002269677
1998	4.559971611071684
1999	4.532279314888007
2000	4.738504738504738
2001	4.651364226938068
2002	4.36163101604278
2003	3.776868853885653
2004	4.373438057836483
2005	3.4067575135336945
2006	3.4621357449529544
2007	3.5395814376706074
2008	3.3828382838283813
2009	4.212860310421282
2010	3.709045950958171
2011	3.5177304964538996
2012	3.438661710037174
2013	3.686779520199394
2014	3.5240040858018364