Year	% of total energy
1960	3.0777318498275017
1961	2.9689718585503777
1962	2.815114926903482
1963	2.6743346657606684
1964	2.5604985581149577
1965	2.4540170458753483
1966	2.3721607703395424
1967	2.251612745882866
1968	2.2094250879716864
1969	2.1249872906784066
1970	2.3810339489919703
1971	12.641480938155368
1972	12.333587017407968
1973	11.923398587204938
1974	12.179849327531132
1975	12.36742150539847
1976	11.952573248176707
1977	11.801712401560469
1978	11.641430952714137
1979	11.583510440174807
1980	11.902070251394457
1981	12.218706247304759
1982	12.541008295679859
1983	12.689359185730002
1984	12.590148382273238
1985	12.481664499743344
1986	12.432289076597582
1987	12.292753233677663
1988	12.025800681579806
1989	11.974119798681244
1990	8.992453571023075
1991	9.05904486719153
1992	9.224601978857077
1993	9.139664295384392
1994	9.12898250877519
1995	9.056561273368546
1996	8.94161735091349
1997	8.93786216643853
1998	9.005323878487644
1999	9.09023847315949
2000	8.933036433921478
2001	8.725073515970742
2002	8.631589703764146
2003	8.476132001758154
2004	8.199384157478033
2005	8.100153669349643
2006	8.040687426061464
2007	7.891813629539812
2008	7.856505976155631
2009	7.955054938006474
2010	7.730673751388581
2011	7.60018784537769
2012	7.572603867933648
2013	7.5784561198275595
2014	7.4636668141000255
2015	3.9352141740078643