Year	% of total energy
1971	21.83485095627127
1972	19.31791435353643
1973	21.41140124592489
1974	20.54244142455226
1975	18.860902709334837
1976	17.123699799856833
1977	16.15459324198317
1978	14.459464825208334
1979	16.579507224634437
1980	12.211494040318966
1981	13.909401230802324
1982	13.935757370848762
1983	13.187148925907085
1984	12.68255027180299
1985	13.803172776009728
1986	12.873524162548053
1987	13.194353081554016
1988	12.866083418945317
1989	12.962279474020702
1990	13.57947230599832
1991	19.39718612752103
1992	26.723153484077745
1993	26.03021343261713
1994	23.363288804039783
1995	23.7413843812739
1996	21.23244995771074
1997	23.747597688495247
1998	20.559971233584786
1999	14.623495514527193
2000	14.383960418567405
2001	14.00476546107614
2002	12.710713457505735
2003	10.045615052002784
2004	10.758313492026844
2005	10.613104915093038
2006	10.872543504261786
2007	10.645002652039098
2008	10.265376296246083
2009	9.793173189991375
2010	9.649620864370855
2011	9.358017947401507
2012	10.348265189770322
2013	8.68356032352784
2014	9.361381299842916