Year	% of total energy
1971	33.21256822973543
1972	31.490038171373122
1973	29.314033577171497
1974	28.397355561370286
1975	27.788078156744422
1976	26.314581782296308
1977	25.598876926585568
1978	24.47854878411957
1979	23.81507484624611
1980	23.143323137228485
1981	23.006655812010187
1982	22.83245935992303
1983	24.219240079104452
1984	24.77452912514658
1985	24.38857554475661
1986	23.821530873328918
1987	23.583894230317583
1988	22.977631372747076
1989	22.759548390441193
1990	17.730891579520208
1991	17.00351591992512
1992	16.55822522842033
1993	15.938019429680658
1994	15.783702137102383
1995	15.52323360042229
1996	15.154713109836333
1997	14.413464289105812
1998	14.280921301779
1999	14.417684827131172
2000	13.739986105662872
2001	13.719355476725475
2002	14.163726506365201
2003	14.16878991092249
2004	13.98820829572758
2005	13.793250338186365
2006	13.773733696416857
2007	14.06323949177869
2008	14.04869472504958
2009	14.2293173902571
2010	14.53526957491538
2011	13.925365727921596
2012	13.44672207181004
2013	13.372209246806499
2014	13.287661150712943
2015	3.757445200113104