Year	% of total fuel combustion
1990	11.98220739505143
1991	9.650479430869163
1992	8.350906790383803
1993	10.016510731975783
1994	8.84855360181509
1995	11.215538847117793
1996	10.99290780141844
1997	8.90909090909091
1998	8.103015075376884
1999	5.6375838926174495
2000	6.271536871123364
2001	7.2812291249165
2002	5.353466026080989
2003	5.676328502415459
2004	5.896510228640192
2005	6.242568370986921
2006	6.696716033483581
2007	6.928645294725958
2008	6.869369369369369
2009	5.284552845528456
2010	4.075067024128687
2011	5.251270468661772
2012	5.170316301703163
2013	5.726405090137859
2014	4.851598173515981