Year	% of total energy
1971	49.8123321189573
1972	43.83455034905615
1973	40.53290311328159
1974	39.836601383027
1975	39.58780253862221
1976	39.767346101647966
1977	38.95428130975297
1978	38.6756848177162
1979	38.23085773678895
1980	37.234274853566205
1981	40.468114576969285
1982	45.72976175712731
1983	39.19493623116133
1984	39.41790732201783
1985	29.441964628466604
1986	27.850372748163572
1987	24.29117586563602
1988	20.664784162621487
1989	20.37618313690419
1990	15.108252429119041
1991	14.697141382287517
1992	13.370309831688004
1993	14.684984642689644
1994	13.657300174413182
1995	12.414312451356826
1996	11.541624211537826
1997	10.461534866871586
1998	11.241651744257517
1999	10.803454149784613
2000	10.74408920113401
2001	10.936246860134375
2002	10.683655895570986
2003	10.9634913568106
2004	12.494019920601216
2005	11.143369637369393
2006	10.750560245042513
2007	10.749642036076985
2008	10.551615938440232
2009	10.572737340301439
2010	10.170928163958688
2011	9.735764282804512
2012	9.452848736281846
2013	10.66517846487393
2014	10.049577303931075