Year	% of total fuel combustion
1971	26.132842757552282
1972	25.377015080603222
1973	25.73622545915136
1974	26.827501267840326
1975	26.505153962313702
1976	25.968879305320822
1977	25.932168760854015
1978	25.108809192200557
1979	28.52671266984421
1980	28.49645520670288
1981	28.57222563186966
1982	27.64505984986813
1983	24.617579641670954
1984	19.421478033303227
1985	19.8736767191531
1986	19.392754263125802
1987	19.566121018982205
1988	19.10174969352502
1989	19.90996557507282
1990	21.615261635739817
1991	22.680616581430527
1992	21.906165561287153
1993	20.475988229226708
1994	20.028083447959652
1995	20.72502557347645
1996	21.156775263179178
1997	19.766445390941765
1998	20.709002805406783
1999	21.321313748975605
2000	20.371615426929893
2001	20.935549509590984
2002	20.504316120104555
2003	19.697228691694626
2004	18.65137892716436
2005	19.10860366713681
2006	19.333739516880513
2007	20.71900876189821
2008	20.261630218687873
2009	19.725739194926476
2010	20.86866834746734
2011	20.8295962566659
2012	20.46867746385861
2013	20.26003149932918
2014	19.531755512418496