Year	% of total energy
1971	22.011200752177178
1972	20.931153127929566
1973	19.294515912550843
1974	18.168406655742828
1975	17.904343235503294
1976	16.93593213234557
1977	15.75282514359203
1978	15.251279571677264
1979	14.63035423059122
1980	14.739596703733268
1981	15.024159215120134
1982	14.820951522700621
1983	14.583700736825044
1984	14.465773664743352
1985	14.506416448632006
1986	14.364256822100874
1987	14.320791381236365
1988	13.90461652320023
1989	13.043343468349827
1990	12.744023638332774
1991	13.115491654508169
1992	12.54134262351374
1993	12.272723244082744
1994	11.617657278940507
1995	11.963911167730675
1996	11.558584451184531
1997	11.369078616214184
1998	11.299218467586583
1999	10.756088269230348
2000	10.822118696681752
2001	10.316957594734008
2002	10.248316758864963
2003	10.395751341791295
2004	16.37627976175196
2005	14.518785340088403
2006	13.237763211056478
2007	11.939263930800518
2008	10.570481858921598
2009	9.473476432721704
2010	8.691491610106631
2011	7.785000152679769
2012	7.424131161411436
2013	7.260601094120622
2014	7.151581065889164