Year	% of total energy
1971	84.60013671535229
1972	84.52431496740911
1973	83.78397316102898
1974	83.84080470913452
1975	84.96515022197738
1976	84.4888166691032
1977	84.56646312011567
1978	84.42698582578367
1979	84.30652537431389
1980	83.33414087607916
1981	83.68550309796439
1982	83.5085764967378
1983	83.5803357344206
1984	83.30753747381391
1985	83.05383527549965
1986	82.53371064578683
1987	82.48712985427743
1988	81.78700375051773
1989	82.02145719483961
1990	67.60028719443672
1991	67.8431204500962
1992	67.93543644853298
1993	68.04578986138816
1994	67.66855521784629
1995	66.56245656908492
1996	66.36860004310604
1997	66.17800046205271
1998	66.70180273505002
1999	65.89088987033324
2000	66.12487555591676
2001	65.06929479032752
2002	64.84268358378873
2003	64.06056879072314
2004	63.425753391419356
2005	63.32797576972648
2006	62.4433442150251
2007	61.825498090004814
2008	61.37029316412778
2009	60.93286732607128
2010	59.999334810509104
2011	59.85945684447379
2012	55.80214778503326
2013	55.723919581623214
2014	56.71727669900203