Year	% of total fuel combustion
1971	8.229631740603526
1972	8.150753668981825
1973	8.321678986975675
1974	8.215783098854002
1975	7.926839159704763
1976	7.495415349799057
1977	7.329650602660162
1978	7.018215026162504
1979	7.036959197766237
1980	6.34157869859776
1981	7.014695726972051
1982	6.948570097268333
1983	6.876976860329615
1984	6.832554232142949
1985	6.450862491845394
1986	6.50500775440987
1987	6.151214133044114
1988	5.997913401957349
1989	5.65860100015895
1990	6.128105071303467
1991	5.922605090881808
1992	5.589169156079886
1993	5.295597274741385
1994	5.451855260592932
1995	4.784838413935366
1996	3.363514706301073
1997	4.172042771032295
1998	4.2808303074184355
1999	4.635889939144254
2000	3.0763377805764365
2001	3.090065755640656
2002	3.096485190672282
2003	3.049712646027321
2004	2.9655918724770576
2005	2.86753868535066
2006	2.701112171246695
2007	2.47793163364903
2008	2.440779162232857
2009	2.3776972963030176
2010	2.246811472557168
2011	2.1035883632887664
2012	2.1770319684447013
2013	2.1906669273780524
2014	2.1699292890978708