Year	% of total energy
1971	63.27972705043409
1972	62.86716760953987
1973	61.285600715464085
1974	60.082159929902666
1975	59.14848122447413
1976	57.82459505523618
1977	56.4344026564296
1978	56.11796246282446
1979	54.46148658666301
1980	53.742611692522836
1981	52.04979674179909
1982	50.40727416745798
1983	50.47372336648636
1984	49.55575656063504
1985	48.02031617601554
1986	46.99725933360133
1987	46.01751218606182
1988	45.19863435020219
1989	43.7704773853821
1990	29.53000028328281
1991	29.112556028387033
1992	29.77074897303456
1993	29.927205280793217
1994	30.38559788846917
1995	29.71214833301358
1996	29.75130577616495
1997	29.31317418553855
1998	29.356490150831405
1999	28.4467540971339
2000	28.376040552547035
2001	28.026807731707105
2002	27.64724235800769
2003	27.290117987827248
2004	26.50961259199601
2005	25.9806377849644
2006	25.613841675108564
2007	25.02228946770448
2008	24.600209653124423
2009	24.18932524961095
2010	23.5271654864844
2011	23.52016487614427
2012	23.217371819086985
2013	23.314369798406318
2014	22.8998057546368