Year	% of total energy
1971	19.066346866071747
1972	19.238320461694872
1973	19.12400513220627
1974	18.064156677887905
1975	16.89705661865713
1976	17.081139605847365
1977	16.601975781854495
1978	15.320066696628734
1979	14.527235093939517
1980	30.12137057235088
1981	31.277286854181074
1982	31.900852053820717
1983	35.35766110788557
1984	35.40577570059039
1985	36.50179461793189
1986	39.221331913914725
1987	29.703597445658623
1988	31.656605635622732
1989	28.283673613098266
1990	27.666850035106993
1991	28.106773175285888
1992	25.733398024669007
1993	25.83625061773039
1994	23.831176700832827
1995	21.665300223032844
1996	19.349799705333474
1997	17.510869699668355
1998	17.094034637976353
1999	17.16249206330382
2000	12.344639941090055
2001	16.080116567260816
2002	13.554206468861071
2003	13.15735682604526
2004	13.255057512027646
2005	12.318399289692358
2006	10.220039078776978
2007	12.755590599761895
2008	12.19092371312924
2009	12.04572672651537
2010	12.746522961322329
2011	12.55762278812794
2012	11.390463274486338
2013	12.226747765549522
2014	11.14142564397645