Year	% of total energy
1971	98.1862774849729
1972	97.6311447015045
1973	96.83327635480649
1974	97.01952125247027
1975	97.3585522491432
1976	97.76976389825897
1977	97.50189870164972
1978	97.54833411849702
1979	96.544264102705
1980	96.13245001754808
1981	96.53358791128277
1982	95.95902888852585
1983	94.90308540528864
1984	94.55809945522569
1985	95.7125180672174
1986	94.59370731372026
1987	94.85620355617918
1988	94.68569374163121
1989	95.46336099206187
1990	93.65646324307743
1991	92.66439951979989
1992	92.40096186262392
1993	91.95445850851537
1994	90.70973183345802
1995	89.82758769683159
1996	89.59975487000895
1997	88.65534191373939
1998	88.26396151346559
1999	85.45534302024899
2000	85.72955512126413
2001	85.11867041467508
2002	87.11732996198973
2003	86.54812112171652
2004	87.16677590391892
2005	86.13877931845609
2006	87.63078411163397
2007	87.72089882189086
2008	86.55150192896214
2009	85.01167645173788
2010	83.31227026334584
2011	82.47474653809282
2012	79.42596889402746
2013	80.02844958065
2014	77.93562620752724