Year	% of total energy use
1960	2.8136395448183595
1961	2.8910422317771944
1962	2.854967234679878
1963	2.856201111564603
1964	2.8629305134319045
1965	3.0695824129736873
1966	3.1658217494813554
1967	3.1434944444464774
1968	3.1374520298732267
1969	3.1534332085388663
1970	3.0625361269506537
1971	3.23988472605574
1972	3.502432377673984
1973	3.6795322206683703
1974	4.3682248270595245
1975	5.22892473336612
1976	5.194268865365735
1977	5.753999230854443
1978	6.311302442307762
1979	6.380187903314916
1980	6.854715905876037
1981	7.859533970706593
1982	8.544700845695479
1983	9.395086180952234
1984	10.243949014544707
1985	11.403088972638761
1986	12.092011630573612
1987	12.365090338022366
1988	12.751809994763692
1989	12.899384470792928
1990	12.35005087546973
1991	12.815428238576164
1992	12.864126341509305
1993	13.251307727579837
1994	13.378466985561612
1995	13.673996424908925
1996	13.789211577644593
1997	13.541509461449532
1998	13.765302230832026
1999	13.931299806450623
2000	13.868551744375699
2001	13.980888452868854
2002	14.005261651806176
2003	13.611624263028295
2004	13.910013037339125
2005	14.012986881974486
2006	14.195772337162307
2007	13.787564502998197
2008	14.077681596765895
2009	14.663035335649097
2010	14.480414012027849
2011	13.948257837626173
2012	13.536000918970988
2013	13.744446388841691
2014	14.097371655857415
2015	14.224925504786713