Year	% of total energy
1971	90.70262032366256
1972	88.3025949497236
1973	88.1859548518603
1974	88.04901406538795
1975	87.30433160335103
1976	91.86238514610156
1977	90.56815050718
1978	89.09276727984332
1979	89.61601623570263
1980	89.57716905105173
1981	91.86105328329901
1982	90.98249055091054
1983	90.76461551960179
1984	90.91847068819031
1985	89.01763442979158
1986	90.50486928133952
1987	91.64495855666877
1988	91.69744362907618
1989	93.5760765415139
1990	80.99788420618607
1991	81.78981493668574
1992	81.72320617488963
1993	81.76347448749716
1994	81.86470846328727
1995	81.5989453338603
1996	77.11284288030382
1997	73.74499155044705
1998	72.92179929538273
1999	66.86312219263704
2000	58.85623931365279
2001	56.957258698648275
2002	54.699269893565564
2003	53.05830037040329
2004	52.24707438852762
2005	53.547554600615776
2006	50.216224578098846
2007	47.5701861527272
2008	47.822260723590446
2009	46.79180339929981
2010	39.883878183370925
2011	39.833927622386476
2012	39.61045139681814
2013	42.34267948644136
2014	41.32632902759631