Year	% of total energy
1971	30.774504865639535
1972	30.631879274739894
1973	28.661098337488454
1974	29.116199364397783
1975	27.700961027293253
1976	28.142768031344474
1977	25.23586238065646
1978	24.411410834169857
1979	24.40575644015909
1980	25.017764455651726
1981	27.240378764895606
1982	27.995251226954675
1983	29.599251528614985
1984	29.89270342575362
1985	28.56025008169114
1986	27.39676401197307
1987	25.996002532768042
1988	26.211395266836746
1989	23.082044262714536
1990	22.981603438110493
1991	22.361485860876325
1992	14.797831948131066
1993	14.606029530794364
1994	15.091453392845702
1995	15.401886624385378
1996	15.666673143056983
1997	10.48184564809474
1998	7.273246236459456
1999	6.604803437966831
2000	8.235312487820089
2001	8.00830517169748
2002	8.03108385735687
2003	8.575178223603148
2004	13.186202426373272
2005	16.164800861725762
2006	16.56011495907195
2007	18.319626026849125
2008	18.070989363817795
2009	16.46196501833847
2010	16.884494942744414
2011	15.436815987303099
2012	12.991409341429122
2013	13.23449996035463
2014	12.784230715369137