Year	% of energy use
1971	98.96650434587922
1972	98.95844459188582
1973	98.96976661751182
1974	99.02459354483896
1975	99.05507263309362
1976	99.1162576316566
1977	99.25020290787981
1978	99.29101084524432
1979	99.1759804163988
1980	99.16373303145426
1981	99.24485442197762
1982	99.29195723988065
1983	99.34563233867244
1984	99.35369971162551
1985	99.36201453927849
1986	99.44625409314398
1987	99.48827584760978
1988	99.53275350545249
1989	99.54063802509287
1990	99.49648450097135
1991	99.51461599849833
1992	99.58922074717213
1993	99.57250468341662
1994	99.57658689379635
1995	99.55928783740401
1996	99.5395627499202
1997	99.51725042869394
1998	99.62714959613214
1999	99.69292115288762
2000	99.6338122436774
2001	99.64614257353692
2002	99.61706042623527
2003	99.62847299992376
2004	99.60124869488051
2005	99.59525361979209
2006	99.51559341202815
2007	99.54604190315439
2008	99.53288187248987
2009	99.55656786426033
2010	99.30006160762554
2011	99.22622240789012
2012	99.32034656680888
2013	99.23166234218907
2014	98.68032373470714