Year	% of total fuel combustion
1971	55.107526881720425
1972	52.037037037037024
1973	51.384083044982695
1974	48.967551622418874
1975	50.51903114186851
1976	47.07158351409978
1977	49.2970946579194
1978	45.9731543624161
1979	44.781931464174455
1980	56.02957906712174
1981	52.037444933920696
1982	53.147208121827404
1983	57.17092337917485
1984	57.88005578800557
1985	58.333333333333336
1986	61.95210122006327
1987	60.8179419525066
1988	65.09584664536742
1989	65.521105715353
1990	62.950058072009284
1991	61.574434918160556
1992	59.77961432506888
1993	58.5174092100337
1994	58.22622107969151
1995	56.89131754705525
1996	55.840784539948075
1997	55.45902114103677
1998	57.14285714285714
1999	52.50651984931905
2000	54.4613710554951
2001	54.31445209105347
2002	56.242150213514186
2003	57.528306432185026
2004	56.378212685687345
2005	56.67752442996743
2006	58.353279080899945
2007	58.63847343991748
2008	55.367769578671755
2009	52.788844621513945
2010	50.5098855359001
2011	53.38958393948211
2012	54.329640515487235
2013	53.80784395102719
2014	53.19415448851775