Year	% of total fuel combustion
1960	1.6664258536820309
1961	1.7585374907201208
1962	1.6548360405870335
1963	1.8312510696559978
1964	1.8286182861828626
1965	1.8602630435641216
1966	1.8901718684501352
1967	1.9426728245729799
1968	1.996357523115717
1969	2.0338763480908124
1970	2.13360985419809
1971	8.520872030501515
1972	8.39397718178265
1973	8.92636411795868
1974	7.86008230452675
1975	8.254292523955444
1976	8.376733482710595
1977	8.214425686954755
1978	8.190497002144252
1979	9.494584350594168
1980	9.301741681422948
1981	8.829838765483357
1982	8.3583999128908
1983	8.30264749361645
1984	7.353096179183136
1985	7.708442579968536
1986	7.218140770583613
1987	7.547800348506909
1988	6.3403822396628176
1989	4.01799432146413
1990	6.764201355320356
1991	6.618828673362087
1992	5.633357110433823
1993	6.381915506318392
1994	5.606685075392864
1995	4.090859077170022
1996	3.5806176375265393
1997	3.6012431535963656
1998	3.231418458060652
1999	3.179607052608628
2000	3.038331890697462
2001	2.881775224355694
2002	2.8054466926534207
2003	2.7888849180394195
2004	2.8713537492941645
2005	2.750125282732653
2006	2.6144957063096324
2007	2.913219840940305
2008	2.6705783105224064
2009	2.6408781946245137
2010	2.544258206158313
2011	2.4068572843173666
2012	2.4125740944190333
2013	2.316618410463099
2014	2.369129146308609