Year	% of total energy
1971	6.625186998504012
1972	8.698186056676624
1973	5.166472122088141
1974	6.453328128733769
1975	7.6723692532125
1976	6.4746370607150325
1977	6.134839330864569
1978	5.9584554924833135
1979	6.005227804066728
1980	4.731558848065366
1981	4.912964532718143
1982	4.270774833705812
1983	4.119956446393791
1984	4.013574870048571
1985	3.9586988455569827
1986	3.7307238583103945
1987	3.2753048032992846
1988	3.134635862479243
1989	3.1736766673585195
1990	1.4926928946895177
1991	1.2265401876784985
1992	1.1229968613078822
1993	1.297360325768222
1994	1.2425902631636472
1995	1.0978791542836543
1996	1.0752722071167211
1997	1.0119479336901414
1998	0.9471231242390361
1999	0.839109226444085
2000	0.790387932205875
2001	0.7265975068820107
2002	0.7644933439922006
2003	0.7140332235458721
2004	0.6779927392106394
2005	0.6588812726398879
2006	0.6363177572982488
2007	0.6715619328452557
2008	0.6570610462024518
2009	0.6103507250515364
2010	0.6480801964770789
2011	0.7896384725421821
2012	0.8977013016016935
2013	0.6675031476923758