Year	% of total fuel combustion
1991	49.557522123893804
1992	54.47154471544716
1993	46.15384615384615
1994	48.484848484848484
1995	59.77653631284916
1996	30.208333333333332
1997	29.441624365482237
1998	30.198019801980198
1999	28.787878787878785
2000	30.526315789473685
2001	32.51028806584362
2002	31.603773584905653
2003	32.14285714285714
2004	32.47863247863248
2005	26.90763052208835
2006	27.999999999999996
2007	28.571428571428577
2008	30.47945205479452
2009	31.543624161073826
2010	32.899022801302934
2011	32.587859424920126
2012	33.641975308641975
2013	34.30232558139535
2014	34.81894150417828