Year	% of energy use
1960	65.31670162405683
1961	68.6299659882852
1962	72.57889866491057
1963	74.4074707397282
1964	74.87700283750112
1965	76.62542371999359
1966	77.78895990892646
1967	79.29651296954268
1968	80.56229872093283
1969	81.14693754367687
1970	81.78305684979053
1971	81.46970385590808
1972	81.95908706133407
1973	82.88762603346639
1974	82.59886134812895
1975	82.03147271320633
1976	82.76634959772714
1977	83.05379767836565
1978	83.4055147196634
1979	84.39997526290749
1980	84.79396884028709
1981	83.730668876626
1982	81.90729018551606
1983	82.7731712175379
1984	82.24245502361342
1985	82.39051609716749
1986	81.0349454334449
1987	82.24570295430144
1988	81.73559446148573
1989	82.65964035596588
1990	82.72796816030288
1991	82.63412124703243
1992	81.73618649909665
1993	80.93875062377828
1994	79.87048441757781
1995	81.51230787201726
1996	80.96096132852108
1997	81.1459930992474
1998	81.7286017337053
1999	82.63902248915302
2000	83.57703846799677
2001	84.4230696083365
2002	83.70034230769468
2003	83.53825705444659
2004	84.06483707047502
2005	83.79208330426663
2006	83.71512533565478
2007	83.08543015655388
2008	81.88238606319652
2009	81.33076624290712
2010	81.00267181727541
2011	80.9821353995273
2012	78.3338476613038
2013	76.33877418500904
2014	75.00130370140964
2015	76.4179821065515