Year	% of total fuel combustion
1971	10.03328578221588
1972	11.96705426356589
1973	13.350000000000001
1974	12.385786802030458
1975	12.682641729982466
1976	12.800447177193963
1977	12.854847348687734
1978	11.76470588235294
1979	10.81474296799224
1980	10.327102803738319
1981	10.380460310004697
1982	12.132752992383026
1983	10.415570752235665
1984	9.945571499257792
1985	9.327217125382264
1986	9.643916913946589
1987	10.24390243902439
1988	9.11290322580645
1989	8.1
1990	10.023785253143053
1991	11.146496815286623
1992	12.568493150684931
1993	12.273901808785528
1994	11.797587525742864
1995	10.955207771181868
1996	8.857808857808857
1997	8.660461351679483
1998	7.348242811501598
1999	7.639680729760548
2000	8.599053692655833
2001	9.065580797256754
2002	8.605779371440626
2003	7.901234567901234
2004	7.969248078004876
2005	7.442116868798235
2006	7.348185411426518
2007	7.104345068189026
2008	6.871147195910389
2009	7.368749026328089
2010	7.420906837731447
2011	7.795484727755643
2012	6.941206941206941
2013	6.572369223265455
2014	6.463527239150508