Year	% of total energy
1971	69.65335714836371
1972	69.01322554092081
1973	68.13132207717794
1974	68.2795289597167
1975	67.86269762764847
1976	69.83063101632312
1977	67.77327999790101
1978	69.76427934363636
1979	70.96502972041478
1980	70.86708110101813
1981	69.31017206560685
1982	69.14023560924414
1983	83.65293137292018
1984	80.99769195307861
1985	75.71892934172847
1986	75.50715347743918
1987	72.29923759369524
1988	76.62189597063735
1989	73.73970819665034
1990	57.415593514536766
1991	57.603117826609804
1992	57.44388003876089
1993	56.632021418612844
1994	56.2409373686348
1995	55.20887354039786
1996	54.640274278175816
1997	53.49492565575416
1998	51.944039361117476
1999	51.1112242444002
2000	52.77147636068386
2001	49.38750684303464
2002	46.86481441367975
2003	46.822762573341976
2004	44.39504013606462
2005	42.56053446602758
2006	38.1100974497201
2007	36.78225187826634
2008	35.79364674363717
2009	32.65362225287508
2010	29.79392012943547
2011	28.734726338559536
2012	26.612823494352543
2013	26.171405950750938
2014	26.875504838982312