Year	% of total fuel combustion
1971	13.98176291793313
1972	17.42738589211618
1973	24.489795918367346
1974	24.17582417582417
1975	28.674948240165634
1976	29.594721960414706
1977	28.006872852233677
1978	28.77813504823151
1979	26.556639159789945
1980	28.801169590643276
1981	34.41558441558442
1982	35.69951757408683
1983	37.279267495094835
1984	38.89955214331413
1985	37.24646588813768
1986	40.35820895522389
1987	43.41491841491841
1988	42.98440979955456
1989	38.53683668212262
1990	40.30534351145039
1991	38.10679611650485
1992	38.04789877993674
1993	40.49912434325744
1994	40.81632653061225
1995	44.84081319524357
1996	38.715953307392994
1997	39.57557706626955
1998	38.56209150326798
1999	37.82668500687758
2000	38.05010155721056
2001	41.06865486175831
2002	42.18421842184219
2003	43.92014519056261
2004	43.923945990631026
2005	43.32733350475701
2006	42.284718765555
2007	40.82031249999999
2008	39.672514619883046
2009	37.14887640449439
2010	38.67247007616975
2011	39.77317946677278
2012	39.710144927536234
2013	37.88389142064593
2014	40.59499152701939