Year	% of energy use
1971	9.29737967633745
1972	11.697405050276402
1973	11.814045148139694
1974	11.950985934612044
1975	12.695668396648966
1976	8.13761485389845
1977	9.431849492820016
1978	10.907232720156681
1979	10.383983764297362
1980	10.422830948948278
1981	-8.054519345347204
1982	-7.6539772076508985
1983	7.606532399470208
1984	8.735904842820734
1985	-10.443362909875384
1986	-14.341231119735646
1987	-11.741569938115255
1988	-6.641217792232966
1989	-5.499503108716379
1990	-6.757056909737156
1991	-6.927512619570209
1992	-3.0066713340932334
1993	-3.885710861504532
1994	-2.3892714888088826
1995	-0.258035873808226
1996	10.604862313190463
1997	15.40843539195304
1998	15.970461499321967
1999	22.232050079392245
2000	27.108444673092347
2001	29.325136847856292
2002	31.673683009838804
2003	33.92686169989788
2004	34.81831997928131
2005	33.0971857951374
2006	38.04305955310081
2007	41.222259232783536
2008	40.81287755334297
2009	41.967455195423234
2010	43.755173319902774
2011	43.711480545635936
2012	44.15648807062372
2013	45.125907095508104
2014	46.59070712762667