Year	% of total energy
1971	48.31912206863713
1972	49.4587833688311
1973	45.75414346106374
1974	47.014495103762094
1975	45.68014914797429
1976	44.902627691230016
1977	44.10228518145262
1978	44.38977670048374
1979	42.88634428191687
1980	42.03336422820267
1981	43.19670883435664
1982	42.786018883019175
1983	40.90000724336868
1984	46.16887706903343
1985	44.976790167679916
1986	45.72369747350259
1987	43.069414004908964
1988	41.14446842683936
1989	39.51157375655349
1990	31.68459763948442
1991	30.904361294953166
1992	28.869262086334015
1993	28.200008460933773
1994	25.672860164479093
1995	23.890658358647006
1996	22.404116535669033
1997	20.627498831899505
1998	19.40715589512547
1999	18.365358964292618
2000	17.231380098152922
2001	17.458253492247962
2002	16.699652117900932
2003	16.13646764259586
2004	15.671702297683085
2005	15.139823558222776
2006	14.927614336948864
2007	14.722694174160642
2008	13.98916351122503
2009	14.789046714442232
2010	13.735634870254168
2011	13.61415542487813
2012	13.554190593438346
2013	13.589508561415665
2014	13.009557443298084