Year	% of total fuel combustion
1971	10.869565217391305
1972	15.339233038348082
1973	15.580736543909351
1974	18.33910034602076
1975	18.18181818181818
1976	15.241635687732341
1977	15.862068965517242
1978	17.065868263473053
1979	15.745856353591158
1980	14.088397790055248
1981	17.287234042553195
1982	16.113744075829388
1983	14.63963963963964
1984	16.230366492146597
1985	9.195402298850574
1986	8.454810495626822
1987	6.818181818181819
1988	9.018567639257295
1989	11.420612813370473
1990	10.899182561307903
1991	9.68586387434555
1992	12.219959266802444
1993	13.513513513513514
1994	11.688311688311689
1995	8.990825688073393
1996	9.273182957393484
1997	10.062893081761008
1998	12
1999	10.87912087912088
2000	7.6996197718631185
2001	8.269230769230768
2002	8.113035551504101
2003	9.9581589958159
2004	6.823720552396425
2005	8.88722927557879
2006	9.932088285229202
2007	8.816705336426914
2008	8.910891089108912
2009	8.910034602076125
2010	8.225806451612904
2011	6.8847989093387865
2012	7.036114570361146
2013	7.3508005822416305
2014	5.913978494623656