Year	% of total energy
1971	51.751628860125166
1972	51.76251167978032
1973	50.69669502183209
1974	50.58395473228705
1975	50.56940132006461
1976	49.852932168991295
1977	49.86095568157237
1978	49.09224841384064
1979	48.94289652352911
1980	48.19018874927362
1981	47.041462447971924
1982	45.925724162234935
1983	46.14923339747779
1984	45.185647102043305
1985	45.65092929086663
1986	45.08891092817496
1987	44.94298187573274
1988	44.62192303570639
1989	46.52685425908952
1990	37.22339194891012
1991	36.90782540602008
1992	38.87692719845397
1993	38.27985000500732
1994	38.25648796600835
1995	37.62907573003487
1996	37.75714076028217
1997	37.79228267174537
1998	38.790477940825674
1999	38.93286755583629
2000	39.72770085032056
2001	39.57487294757415
2002	40.2954368474212
2003	39.594295372112406
2004	38.31251420121853
2005	38.80411305620079
2006	39.23391380180874
2007	38.33368223943894
2008	37.379036960565344
2009	38.12490300981691
2010	38.586510833316545
2011	39.036497997541325
2012	37.43455381046897
2013	38.06966036198351
2014	36.08638360015073