Year	% of total fuel combustion
1971	21.318681318681314
1972	21.484375
1973	21.329479768786126
1974	21.572910977607865
1975	20.773638968481375
1976	20.804550995530274
1977	17.432479831638023
1978	17.567567567567565
1979	16.721904188008438
1980	15.489566613162115
1981	16.208925944090243
1982	16.111611161116112
1983	15.575571177504395
1984	13.818096796820198
1985	14.407349316603181
1986	12.325581395348838
1987	11.149188942197851
1988	12.958488908412036
1989	12.388804512909523
1990	12.778052397429562
1991	11.496553257727374
1992	11.376323387872956
1993	11.523477547672751
1994	12.13436928702011
1995	10.97587016869528
1996	11.083603123214626
1997	9.226847918436704
1998	9.405255878284924
1999	9.927710843373495
2000	9.116937914406268
2001	7.909527073337903
2002	7.777923268299071
2003	13.275686673448629
2004	11.689291101055806
2005	9.927797833935017
2006	10.1120765646644
2007	10.702552438716198
2008	10.501695708104315
2009	8.957452102513063
2010	7.765667574931881
2011	12.467917077986176
2012	11.073300836935529
2013	11.622648335745298
2014	12.65272875373337