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	6.106858924382225
1971	5.940476362173365
1972	5.694878132392299
1973	5.432954200562297
1974	5.069955862548578
1975	5.562457753890571
1976	4.996043934921239
1977	5.170635560456956
1978	5.000604774056939
1979	4.94805942173126
1980	4.506324648929251
1981	4.452846975065219
1982	4.6621169098989235
1983	5.029061581652821
1984	4.950353323276367
1985	5.297924972320905
1986	5.0870208340334475
1987	5.21571080157321
1988	4.89754723535096
1989	4.866343027422871
1990	4.318961386517061
1991	4.735583253114987
1992	4.668123296342596
1993	4.417072533752455
1994	4.136185500768602
1995	4.051695840071807
1996	4.1467529776496255
1997	3.912627047459639
1998	3.7960490297734797
1999	3.6099423808579405
2000	3.4363283676008938
2001	3.3672096482215563
2002	3.169761892592576
2003	3.3016824326220875
2004	3.2875645557341384
2005	3.3624084421704725
2006	3.102797032939276
2007	3.4109290038386995
2008	3.8711122429107347
2009	4.259602468934549
2010	4.480498548484457
2011	4.042437413692623
2012	4.480763798255881
2013	4.87499238404191
2014	4.608747978680908
2015	4.81200868391745