Year	% of total energy
1971	80.33372936255054
1972	80.86935586911655
1973	79.9883921992897
1974	79.511622536701
1975	79.91876476556558
1976	79.00257398536347
1977	78.45431972210892
1978	78.42287070921117
1979	77.6635984221017
1980	77.72238207659846
1981	77.40040836501626
1982	76.48639971882453
1983	76.7430318623954
1984	75.69033164437558
1985	76.0201386852927
1986	75.27142332810115
1987	74.64185955549125
1988	74.35979720995435
1989	74.46786471106785
1990	55.62804622472533
1991	55.945925504829376
1992	57.33092884023843
1993	58.31170381832734
1994	58.77069364896959
1995	58.18583749153907
1996	57.663922067894525
1997	57.346521686217905
1998	57.191573985556694
1999	56.53758281606926
2000	56.84088778589838
2001	56.03625714383825
2002	55.728937655730036
2003	55.429196397808084
2004	54.51564446019242
2005	53.609321395019975
2006	53.14426281014449
2007	52.314978969563676
2008	52.099211806464545
2009	52.6474885293008
2010	52.0082297305213
2011	52.18189290922724
2012	49.73533019259611
2013	50.23044373651398
2014	51.209646956086765