Year	% of total fuel combustion
1990	13.638785295684604
1991	10.697674418604652
1992	11.424439624005785
1993	13.373083475298126
1994	14.102564102564102
1995	15.393258426966291
1996	13.93258426966292
1997	16.864608076009503
1998	16.313823163138235
1999	15.924426450742239
2000	15.058479532163743
2001	13.793103448275861
2002	14.522821576763487
2003	14.611260053619304
2004	14.83957219251337
2005	14.775725593667547
2006	14.570361145703611
2007	14.23444976076555
2008	13.85390428211587
2009	12.116991643454039
2010	14.091470951792335
2011	14.168937329700274
2012	15.30758226037196
2013	12.879884225759769
2014	12.648809523809524