Year	% of energy use
1971	99.81090341856559
1972	99.82747438059411
1973	99.84854351242399
1974	99.85659979791507
1975	99.87641735095082
1976	99.8791732975053
1977	99.93003667774167
1978	99.94296089734938
1979	99.94444938762062
1980	99.95447692807946
1981	99.95089302433037
1982	99.95682675238868
1983	99.95003013140366
1984	99.95456894667132
1985	99.95529933969102
1986	99.40583374884251
1987	99.18853244980176
1988	99.32211442822319
1989	98.18391105491234
1990	95.05366740776692
1991	95.31546802175421
1992	95.50318320883969
1993	94.9975769114849
1994	93.26077022245724
1995	93.50368567732865
1996	93.77278147749614
1997	93.59339859916518
1998	93.68126193736856
1999	93.85253035232994
2000	94.12339197740255
2001	94.17177302803252
2002	94.8089857839912
2003	94.45690153085565
2004	95.27091040350179
2005	96.16754141885849
2006	95.76557031389183
2007	96.15613443645948
2008	96.10280022288951
2009	96.06988702971677
2010	96.16476312861244
2011	96.10589545977928
2012	96.532476211611
2013	96.53969127791058
2014	96.81229729348095