Year	% of energy use
1971	90.88422271396806
1972	91.15558986404301
1973	94.01546179141339
1974	92.73667916086433
1975	91.79835359001657
1976	92.33925191108169
1977	90.21727868151346
1978	91.8341845075653
1979	92.33792279726546
1980	92.81994868821826
1981	92.48595982218603
1982	91.04560084245084
1983	92.13496616131265
1984	92.1688215031384
1985	93.36259340227097
1986	94.09213481754615
1987	94.09920518435715
1988	92.08998790582915
1989	92.34737506061553
1990	92.68937174208439
1991	93.75457960280062
1992	93.1807599912021
1993	95.1355499682939
1994	95.16874688811784
1995	95.88551844009848
1996	95.88881325603728
1997	96.14114896505384
1998	96.21347016453508
1999	97.06056977974373
2000	96.48446909286102
2001	96.8036563532807
2002	96.07567866641719
2003	94.80201487284539
2004	95.11085034536646
2005	94.88657965146984
2006	95.16996372096536
2007	94.68392664713424
2008	96.581910157339
2009	97.19152720165599
2010	96.7553750721573
2011	96.76061872914968
2012	96.84893826936687
2013	96.47033485265038
2014	97.86553521755464