Year	% of total fuel combustion
1990	4.102290889717635
1991	4.767441860465117
1992	4.555314533622559
1993	4.770017035775126
1994	5.128205128205126
1995	4.606741573033707
1996	4.606741573033707
1997	4.038004750593824
1998	3.735990037359902
1999	4.183535762483131
2000	4.532163742690058
2001	4.551724137931036
2002	4.287690179806364
2003	4.825737265415548
2004	4.946524064171123
2005	4.881266490765173
2006	4.856787048567872
2007	4.545454545454547
2008	4.282115869017633
2009	4.456824512534819
2010	4.573547589616809
2011	5.177111716621254
2012	5.150214592274678
2013	5.209840810419681
2014	5.357142857142857