Year	% of total energy
1965	4.419918805725243
1966	3.8592194439728758
1967	3.8367426350846214
1968	3.174059370937533
1969	3.9810909848994926
1970	2.752178375052862
1971	2.8466484410684414
1972	2.8100725541942166
1973	3.0071696598260034
1974	2.826964550383649
1975	2.0308319266409405
1976	2.2080000391910635
1977	1.950491546559174
1978	1.6444963587934527
1979	1.9345180394144468
1980	1.8183244124416515
1981	2.008208679206975
1982	1.9430488426635486
1983	1.9743669266522927
1984	2.379943854017248
1985	2.0438520517447936
1986	1.7705318317355139
1987	1.7342167291288533
1988	1.507093346608635
1989	1.6354863384532676
1990	2.163736145380046
1991	2.407956585936588
1992	2.637045296781831
1993	2.6701729409763
1994	2.7637485642683925
1995	2.8609439788184536
1996	2.7240369715653476
1997	2.7048266089164206
1998	2.7424303924321385
1999	2.7874318598817314
2000	2.790746879036591
2001	2.850997883980767
2002	2.8995723996348457
2003	2.886788271780608
2004	2.597641867948932
2005	2.5605088867048362
2006	2.949441459439536
2007	3.2574818745847383
2008	3.622980965540839
2009	4.658976131959767
2010	8.090855043815678
2011	9.156470304127275
2012	10.24826848800423
2013	11.248350744064037
2014	9.737939324060072
2015	9.796514414062116