Year	% of total energy
1971	64.3925926064308
1972	64.3448923262292
1973	63.83370709008915
1974	62.879147828443145
1975	62.23704317653398
1976	61.43405726364842
1977	61.04564005181412
1978	61.37670169639851
1979	60.03322807814434
1980	59.27413622842619
1981	57.30103565865157
1982	55.9042905150692
1983	54.969768728097755
1984	53.73351399735442
1985	51.94259739508643
1986	50.94154870314631
1987	49.429046584376636
1988	47.76874548941757
1989	46.37261713607941
1990	44.23432499245686
1991	43.265328428048136
1992	42.25544908295405
1993	41.400590098131204
1994	40.181014322304016
1995	38.479012098892724
1996	37.63383108977693
1997	36.728540221424616
1998	36.27015396792648
1999	34.9193773478702
2000	34.62481790259224
2001	34.48358464612654
2002	34.04514505855634
2003	33.56176937754503
2004	32.42559298515131
2005	31.749473879492623
2006	30.72692821496516
2007	29.59754196411165
2008	28.896300177450886
2009	26.991012452702712
2010	26.278811343205394
2011	25.693084492065378
2012	24.929444473561542
2013	24.733526053708005
2014	23.731333341932196