Year	% of total fuel combustion
1990	74.56213511259384
1991	75.84287039901021
1992	81.82201602699281
1993	78.26086956521738
1994	78.7861599546228
1995	75.56390977443608
1996	74.82269503546097
1997	76.66666666666667
1998	76.94723618090451
1999	79.5302013422819
2000	78.22191592005512
2001	74.4822979291917
2002	75.49759780370624
2003	77.53623188405798
2004	77.19614921780988
2005	76.57550535077289
2006	74.243399871217
2007	77.30093071354705
2008	76.35135135135135
2009	76.42276422764228
2010	80.75067024128687
2011	78.37380011293055
2012	76.82481751824818
2013	78.95015906680807
2014	78.08219178082193