Year	% of energy use
1960	99.9479424243213
1961	99.85313024039961
1962	99.88414783096002
1963	99.99492920043515
1964	99.8235018384541
1965	99.76494298887386
1966	99.77882061666185
1967	99.75968027278104
1968	99.77422143497976
1969	99.81911716308407
1970	99.79893113976038
1971	99.8835598009045
1972	99.86570625417265
1973	99.90881379424854
1974	99.84563589447706
1975	99.83806990786745
1976	99.89720624983921
1977	99.3469456327393
1978	99.39748523151708
1979	99.31174038925484
1980	99.17352144537384
1981	99.02765708325386
1982	99.02693449394992
1983	98.974667404084
1984	98.95905427110056
1985	98.99799664670283
1986	99.13191650116858
1987	98.85440606781742
1988	98.79990823059327
1989	98.92847541382356
1990	99.15002669262053
1991	99.1572125773598
1992	98.74491962106148
1993	98.80042178674032
1994	98.72527115202374
1995	98.58480948173518
1996	98.82989690883026
1997	98.6325884103985
1998	98.23143658127495
1999	98.29009829777033
2000	98.10007989481115
2001	97.95635170576867
2002	98.0136824645482
2003	98.07798691188155
2004	97.99401814462026
2005	97.56751598935404
2006	97.36300833369286
2007	97.2042610917154
2008	97.059477688263
2009	97.1960468219026
2010	97.1974971191104
2011	97.29440497431402
2012	96.99602396644347
2013	96.62699351544323
2014	96.00213677676813
2015	96.31074869209046