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	0.8405129329778016
1971	0.8324790150033838
1972	0.8539050252301308
1973	0.7474512412291132
1974	1.0238563536677485
1975	1.0661190267478238
1976	1.008214516470528
1977	1.0184174435532665
1978	1.0014538842771585
1979	0.9807990015832255
1980	1.2183974296904418
1981	1.3321428495953016
1982	1.4886908396318657
1983	1.444249523449661
1984	1.4972594830406352
1985	1.4575390229170548
1986	1.1925841253439868
1987	1.1197362515561793
1988	1.2381655519667047
1989	1.2015133493676644
1990	0.809147355514624
1991	0.7870052270624129
1992	0.7737367869936993
1993	0.7861732275381169
1994	0.7976777906473945
1995	0.7889693210724642
1996	0.771419159808073
1997	1.1741242136557402
1998	1.2577980691371282
1999	1.2746980165920696
2000	1.3833563868696264
2001	1.3878434419035954
2002	1.4814249018223415
2003	1.9751416068692222
2004	2.187913629689074
2005	2.5900897474814917
2006	3.0331638847858815
2007	3.374822817998907
2008	3.069198126688456
2009	3.520044812641787
2010	3.806143138421214
2011	3.753287375397487
2012	3.7819309035338304
2013	3.6642750227887757
2014	3.9547582368134244
2015	4.069535166954091