Year	% of total energy use
1971	1.3878874686536573
1972	1.5113612357519215
1973	1.16973361130543
1974	1.308684341736996
1975	1.2552358236699963
1976	1.31474613303785
1977	1.3512485935393574
1978	1.4219984715530296
1979	1.212244178352594
1980	1.1197120048844134
1981	1.0118357754546239
1982	0.9059685275201796
1983	0.8277681660329251
1984	0.7881255018318452
1985	0.8111731182215793
1986	0.863139596802348
1987	0.8999948092036512
1988	0.8119249306284438
1989	0.7941146530263575
1990	0.6982477246242985
1991	0.6555176536224151
1992	0.6381107617923603
1993	0.604157262951093
1994	0.5392185606824837
1995	0.5239354659145073
1996	0.558808014683342
1997	0.5369590467406578
1998	0.5394570977016165
1999	0.5050770924228678
2000	0.4692912685069163
2001	0.4865780998137818
2002	0.4754534191142567
2003	0.5393469689045506
2004	0.5181134109386211
2005	0.5919528913214022
2006	0.5844027660514993
2007	0.5678233428008507
2008	0.4263760296916721
2009	0.43353944497397356
2010	0.49062801481636326
2011	0.503572669614274
2012	0.5251085850796312
2013	0.64861027640879
2014	0.5980394660328675
2015	5.245322035134604