Year	% of total fuel combustion
1990	16.827072337783296
1991	17.852975495915985
1992	14.620187304890738
1993	15.354586857514638
1994	15.523215523215525
1995	14.370811615785556
1996	11.646297627606039
1997	10.25830258302583
1998	8.047585724282715
1999	8.823529411764703
2000	8.317025440313113
2001	7.35970561177553
2002	7.959743824336687
2003	8.234217749313814
2004	7.9584775086505175
2005	7.986960065199675
2006	8.790322580645162
2007	8.379888268156426
2008	8.025682182985554
2009	8.77659574468085
2010	9.269893355209186
2011	10.13215859030837
2012	9.507042253521128
2013	9.878844361602983
2014	9.311348205625606