Year	% of total fuel combustion
1971	57.49999999999999
1972	61.53846153846154
1973	77.94117647058823
1974	84.21052631578948
1975	86.52482269503547
1976	87.56756756756756
1977	88.94472361809045
1978	87.70053475935828
1979	85.71428571428571
1980	81.43939393939394
1981	83.39768339768341
1982	81.1808118081181
1983	80.06872852233677
1984	81.56996587030714
1985	79.66101694915253
1986	79.93197278911563
1987	79.59866220735785
1988	78.59424920127796
1989	77.491961414791
1990	77.91411042944786
1991	77.2189349112426
1992	75.69832402234637
1993	76.42487046632125
1994	76.32850241545894
1995	77.11111111111111
1996	76.00849256900213
1997	76.03143418467585
1998	75.1740139211137
1999	75.17899761336515
2000	77.14932126696831
2001	76.33410672853829
2002	75.45871559633028
2003	78.66666666666666
2004	76.82926829268293
2005	76.97095435684646
2006	58.391123439667126
2007	54.97076023391813
2008	54.43213296398892
2009	68.90982503364737
2010	75.21865889212827
2011	73.60912981455064
2012	71.44906743185079
2013	72.4087591240876
2014	72.08955223880596