Year	% of total energy
1971	55.47678246258111
1972	55.79946761253448
1973	55.22954000727035
1974	54.65204954177782
1975	54.7707816476117
1976	53.71402396446877
1977	52.860210781525325
1978	51.92494056473161
1979	50.3699665265987
1980	50.03458560510504
1981	49.64502475613999
1982	48.74893251548711
1983	48.1877039085266
1984	47.71091644182791
1985	47.9481504283384
1986	48.654910613424725
1987	49.3192639617325
1988	49.056951511270455
1989	49.819538059922934
1990	38.862354361318076
1991	39.58940290124347
1992	42.189729416869966
1993	44.036760710038564
1994	45.17277558636792
1995	45.71142284357708
1996	47.159437299494314
1997	47.466575434269586
1998	48.545658039888146
1999	48.05724257101367
2000	48.591453672630415
2001	48.163378431137346
2002	48.40527058381713
2003	48.51965725624054
2004	48.28627931312637
2005	47.14821906718988
2006	47.045268954647945
2007	48.099052870832054
2008	47.5437729513337
2009	48.22201885234506
2010	48.72779883537163
2011	51.69615561606955
2012	49.26517309143533
2013	51.79020930278168
2014	55.168381228712