Year	% of total energy
1971	75.43648288921212
1972	72.95858546380776
1973	70.20470192849655
1974	66.53666522220617
1975	64.62015039096654
1976	61.05555715423058
1977	57.27152548110131
1978	55.456974374890365
1979	54.767057828332824
1980	55.44904207450016
1981	55.120017255850804
1982	56.31383641838051
1983	53.542556802884334
1984	51.844032143322806
1985	54.26957676326022
1986	50.991469419702575
1987	49.85447306809228
1988	45.08859716034025
1989	43.661334368489655
1990	36.401297019391514
1991	32.6383
1992	32.71077171747758
1993	29.726698150059804
1994	26.40021821888571
1995	28.42074538861415
1996	25.034057320385617
1997	26.00520962804084
1998	22.31167288678617
1999	13.91382792404463
2000	12.374213593693705
2001	12.08101494687149
2002	10.678125338682538
2003	11.137242232758854
2004	11.206958033116193
2005	10.199475287730857
2006	9.379362956605334
2007	8.654978623240622
2008	6.5400764048706925
2009	6.555803748669582
2010	7.086461130381244
2011	6.445637628655016
2012	5.922438900347947
2013	5.611343440647952
2014	5.095081809294792