Year	% of total fuel combustion
1971	10.72365954255718
1972	10.651537335285505
1973	10.293091416608513
1974	9.899383317104835
1975	9.225874867444329
1976	8.660892738174551
1977	8.220502901353964
1978	7.543168736746441
1979	7.102187593646988
1980	6.408045977011495
1981	6.784998568565703
1982	6.537052690898844
1983	6.58458244111349
1984	6.64196877480815
1985	6.764631365594122
1986	6.623505976095618
1987	6.500821403426425
1988	6.3602599814298975
1989	7.628819986616106
1990	8.038444735692442
1991	7.975589225589225
1992	7.866531850353893
1993	7.941684250911182
1994	7.1688709986582335
1995	7.107438016528926
1996	8.002207505518763
1997	7.586558044806517
1998	8.055274688237276
1999	9.190540280715249
2000	8.824072364777551
2001	7.871133077063884
2002	9.255379927632832
2003	9.355709876543209
2004	8.524148547238791
2005	8.549561321635244
2006	9.990680335507921
2007	9.75164353542732
2008	9.457029845379362
2009	8.402507199728952
2010	8.17140009965122
2011	8.258143447010246
2012	8.096917650667075
2013	8.67786087201919
2014	7.90344827586207