Year	% of total energy
1971	80.33834675206809
1972	80.45684930378029
1973	79.364464079539
1974	78.7709700189291
1975	78.61986574369514
1976	77.71647230593958
1977	76.89720606597025
1978	76.46905069940154
1979	75.5821719374094
1980	75.00062876387678
1981	74.0841388305671
1982	73.01992615760668
1983	72.91780617376267
1984	72.81843954120473
1985	72.51839233288851
1986	72.10821632790343
1987	70.76406506524698
1988	70.42952977563226
1989	70.03344456894058
1990	50.44411422131253
1991	50.25016994710642
1992	51.011376554005444
1993	51.32216092950484
1994	52.31225465660277
1995	52.68227255196687
1996	52.04312008488795
1997	51.91536979631907
1998	51.567794364087625
1999	50.935409440179136
2000	51.19830730595736
2001	50.86447371178004
2002	50.81628709443754
2003	50.65498846172678
2004	50.12213944291319
2005	50.04298770290263
2006	49.83957925533146
2007	49.38441468734336
2008	49.60097558620107
2009	50.973739735062296
2010	50.5891881084389
2011	50.39955558588187
2012	49.400196043020934
2013	50.128525083162735
2014	54.159948658432285