Year	% of total energy
1971	3.2911594802487154
1972	3.336126394170571
1973	2.861469893478775
1974	2.561460076579762
1975	2.429324662963316
1976	2.142620629137939
1977	1.9707497970677612
1978	1.8711333835110002
1979	1.5082476852366642
1980	1.4647864547646368
1981	1.4293805487401139
1982	1.6432643922559516
1983	1.630225237146611
1984	1.4955570157474387
1985	1.8369487084250342
1986	1.6202428663004778
1987	1.3710891120344793
1988	1.2805134365454387
1989	0.9406740741583361
1990	0.9453474931054976
1991	1.3486254629206744
1992	1.461265181377311
1993	2.1917712736017716
1994	2.719767179090236
1995	2.831695301552447
1996	5.28553103646237
1997	7.390235568443095
1998	7.2490081106988455
1999	7.7424787703597575
2000	7.578557857844707
2001	5.764151616807292
2002	5.957142013630574
2003	7.157767314266447
2004	7.929717327631844
2005	8.23635244549982
2006	7.717420350527059
2007	8.224334847018556
2008	9.842172852120825
2009	11.213421375371048
2010	11.567291763574849
2011	10.226053102677957
2012	11.08629359683735
2013	11.647093500603662
2014	11.568063357287151