Year	% of total energy use
1960	0.024413907251679905
1961	0.023963480341854696
1962	0.020950989395482438
1963	0.01833700897967594
1964	0.017510819854142202
1965	0.016004848799215748
1966	0.015194738651854289
1967	0.014525504793382802
1968	0.011587411169597097
1969	0.010454433561162995
1970	0.010544483082005273
1971	0.011153619273799953
1972	0.010716214343600981
1973	0.010868043366231105
1974	0.01172320890354997
1975	0.01181267839204723
1976	0.01086331684221485
1977	0.009707954257474137
1978	0.012570930304679814
1979	0.0171416956578957
1980	0.024666526332248494
1981	0.028744227191415304
1982	0.031915384379982856
1983	0.0395274581878898
1984	0.039132833217124914
1985	0.04327035599259196
1986	0.0755272233833959
1987	0.09658211642334595
1988	0.15740558006983182
1989	0.24449658697715707
1990	1.2672890707441553
1991	1.188787621555475
1992	1.4181403402079267
1993	1.4880675422118996
1994	1.3810835926943796
1995	1.6100972955662016
1996	1.360345552250067
1997	1.8818191044323165
1998	2.2807258350730875
1999	2.68270666675916
2000	3.517878552603113
2001	3.4767406773874403
2002	3.7565678510020004
2003	3.5773974099044508
2004	4.4503748931896725
2005	5.080613649532744
2006	3.9761962904788493
2007	4.86685973951037
2008	5.204404119569619
2009	5.094805109696785
2010	4.99498635503965
2011	6.633674500854313
2012	7.859529874844975
2013	7.652360447373486
2014	9.89182751386271
2015	11.74894611074175