Year	% of total energy use
1960	0.4882387251785263
1961	0.44648070346940016
1962	0.4521615530550192
1963	0.451209692366231
1964	0.4791653642921996
1965	0.5085500428767886
1966	0.5088385360894374
1967	0.5145516260410231
1968	0.5301589063417255
1969	0.5009738100761425
1970	0.6836546071571904
1971	1.4081989094651457
1972	1.528160478725929
1973	1.6062322823887276
1974	1.7636729851071282
1975	1.7302021449643845
1976	1.7777279020794428
1977	1.806821276339566
1978	1.7526685519675131
1979	1.9486388509123422
1980	2.1954954422466955
1981	2.3508156403423497
1982	2.467156185949113
1983	2.5904618491706124
1984	2.690624859929848
1985	2.8350839703247117
1986	2.8020855755208816
1987	2.769628388583708
1988	2.8276904310042683
1989	2.915966864189317
1990	3.2611302143213226
1991	3.38366720974459
1992	3.4846405163480716
1993	3.5929030992322244
1994	3.7372483899013442
1995	3.7906130333529995
1996	3.8573174602406017
1997	3.9809854638269537
1998	4.048115638030394
1999	4.221470781775752
2000	4.4257092842392565
2001	4.545773729218454
2002	4.5888780958244535
2003	4.5318833038806225
2004	4.434008929283503
2005	4.4180765683831655
2006	4.385193726243766
2007	4.444085744249302
2008	4.661669290755748
2009	4.780781961286415
2010	4.677270169248544
2011	4.687030533956665
2012	4.98227053197516
2013	5.189036092566205
2014	5.575312509361172
2015	6.109663221763978