Year	% of total energy
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0.02867246588288589
1971	0.028416066796697885
1972	0.03142489213236818
1973	0.02519000605754591
1974	0.021275862217645096
1975	0.04573360612771877
1976	0.07045611524569231
1977	0.11835151896540101
1978	0.11312279704358182
1979	0.07463386734924192
1980	0.39329804693789816
1981	0.4576917390909578
1982	0.5138777637493516
1983	0.5051917155193801
1984	0.5795375142972042
1985	0.62647918755825
1986	0.621216677372765
1987	0.6449066793142175
1988	0.6297590751529162
1989	4.080302913322586
1990	4.365470397733351
1991	3.949942788325732
1992	3.533818119650504
1993	3.6929321006769023
1994	3.510439747866863
1995	3.2299909303970336
1996	3.2974459941715066
1997	3.133681107503693
1998	3.1111268296565484
1999	2.9875643833359273
2000	2.8470858301459354
2001	2.792853062449682
2002	2.8373532531887498
2003	2.7989347869447383
2004	2.7032593728312913
2005	2.685701867243789
2006	2.800477511088816
2007	2.931203669489134
2008	3.1484565781994442
2009	3.8807277805309894
2010	4.1408798899215515
2011	4.576472446988659
2012	4.972852782497834
2013	4.244137343345496
2014	4.364659764254833
2015	4.372692502628774