Year	% of total fuel combustion
1971	63.58024691358024
1972	71.25
1973	65.9090909090909
1974	57.777777777777786
1975	56.122448979591844
1976	57.216494845360835
1977	43.046357615894046
1978	51.55038759689923
1979	41.338582677165356
1980	37.59398496240601
1981	34.523809523809526
1982	39.090909090909086
1983	33.62068965517242
1984	31.39013452914798
1985	36.87943262411348
1986	37.18411552346571
1987	36.49122807017544
1988	38.62928348909657
1989	39.3939393939394
1990	26.02040816326531
1991	31.421446384039903
1992	30.591259640102823
1993	28.672985781990523
1994	36.8421052631579
1995	27.365728900255753
1996	23.627684964200473
1997	24.249422632794456
1998	22.25201072386059
1999	24.472573839662445
2000	23.11015118790497
2001	23.856858846918488
2002	26.90909090909091
2003	38.951841359773375
2004	42.432432432432435
2005	39.83739837398374
2006	39.515151515151516
2007	40.04149377593361
2008	43.6917866215072
2009	41.09589041095891
2010	42.36615994712491
2011	44.09203980099503
2012	44.520976831559175
2013	45.13274336283186
2014	43.98963730569948