Year	% of total energy
1971	42.31061555570732
1972	41.342446307401026
1973	40.64138855609761
1974	40.445391662363235
1975	37.91761627129009
1976	37.27939681373036
1977	34.94578203359751
1978	32.829310007139796
1979	32.55462257303807
1980	32.769443077303194
1981	33.24228357705136
1982	32.72854393995151
1983	31.59284822614349
1984	30.388990579843018
1985	29.947222439251135
1986	29.23022212530648
1987	28.31418944696994
1988	27.29238594087124
1989	27.09853915332148
1990	25.118230336258726
1991	25.618760037658816
1992	25.025617266460085
1993	23.729544680542407
1994	22.755759150305778
1995	21.293096537962786
1996	20.643606586714725
1997	20.55061231024985
1998	20.42304211831192
1999	19.92427083446315
2000	19.001193215536738
2001	17.774445870854453
2002	16.634572604425294
2003	14.615885206569555
2004	12.615966665615362
2005	11.293094615079431
2006	10.41683683980432
2007	9.23456458402027
2008	8.501702323606223
2009	7.774459086114674
2010	6.788918016917638
2011	6.185229621647978
2012	5.87713116860693
2013	5.494392038758826
2014	5.069242580621489