Year	% of total energy
1971	39.440907891004485
1972	38.4295677352917
1973	37.9092984153464
1974	37.718210799799564
1975	34.76358618369821
1976	34.1367276601625
1977	31.7689475291903
1978	29.712778631276297
1979	29.622122030391797
1980	30.08816316934026
1981	30.664556154643467
1982	30.07680262211129
1983	29.220695051064894
1984	27.72072600510118
1985	27.270147982330684
1986	26.625988664263602
1987	25.607459753251625
1988	24.565952446674544
1989	24.407414966363554
1990	23.01720555610735
1991	23.863102431570145
1992	23.20858476944919
1993	22.023293055034518
1994	20.979533223668675
1995	19.444882804759008
1996	18.927812063894013
1997	18.947382160005386
1998	18.60051997001108
1999	18.156995387670623
2000	17.271950708042024
2001	15.888205235125216
2002	14.664065478882335
2003	12.355612730452172
2004	10.32455638104706
2005	8.98369368735178
2006	8.088492269996099
2007	6.844378209791955
2008	6.027781705751827
2009	5.294013643866002
2010	4.417393041268709
2011	3.8016496717753125
2012	3.4048456209894904
2013	3.019557619850735
2014	2.883354087676159