Year	% of total energy
1971	82.07015554115733
1972	81.10242464824778
1973	80.07811149256455
1974	79.72861983360184
1975	79.0693272071789
1976	77.2667919388408
1977	76.46384868088751
1978	75.19299210130616
1979	73.947516448857
1980	73.94820170707052
1981	73.90056058099144
1982	73.50875980718168
1983	72.64371899911991
1984	73.17085413009706
1985	72.06803725713593
1986	71.86407962810789
1987	71.96138857498481
1988	70.35215493239672
1989	69.6404242807404
1990	60.91204196615347
1991	62.42203765739951
1992	59.59609203483756
1993	57.906257097222344
1994	58.09198671035739
1995	58.65763022901513
1996	58.49097420870361
1997	56.863463943989125
1998	61.474463234556765
1999	62.956611275420634
2000	62.069998709258584
2001	60.77261001522202
2002	60.999426233079056
2003	61.23516510331241
2004	60.70834845056756
2005	60.710045135274356
2006	61.46888553769402
2007	61.191490466602566
2008	60.67129032426826
2009	60.49585018236804
2010	58.56458714777919
2011	57.72464049873301
2012	54.670109977289
2013	54.61925653979345
2014	54.17277106228363