Year	% of total energy
1960	12.62157954946679
1961	12.412275918209234
1962	11.81514862685393
1963	11.097386627040883
1964	10.56434473542965
1965	10.041201131371368
1966	9.225458445229808
1967	9.34628550117626
1968	8.432936017715155
1969	8.28108388149251
1970	7.727450304260766
1971	8.01720633271
1972	7.857892119818811
1973	9.125081784894547
1974	9.616361489027634
1975	9.136750888187589
1976	8.309077672935528
1977	8.116362431861031
1978	8.943497496370844
1979	9.089126657116896
1980	10.20259390706115
1981	10.097746359431417
1982	10.220910076338559
1983	11.357453896853277
1984	11.760189473912233
1985	11.402805515331602
1986	11.013433855717812
1987	11.360250738804048
1988	11.332303815832635
1989	11.604390060204354
1990	10.649925289504756
1991	10.799722961288307
1992	11.43716201057014
1993	12.198761168819955
1994	11.791017025677345
1995	12.696059642224771
1996	13.08803381861856
1997	13.783515323268174
1998	13.523767405446224
1999	12.991899613186986
2000	15.17421075439139
2001	13.086792791307323
2002	12.710546934087555
2003	13.338183871964073
2004	13.156321073952022
2005	14.345451804556744
2006	15.726889729323625
2007	16.210124547943835
2008	16.171010675734713
2009	18.300318883768945
2010	17.761051755209067
2011	17.1938276965912
2012	18.236076827000915
2013	18.215888882504494
2014	18.523041893644145
2015	18.5513566756651