Year	% of total energy use
1960	0.21663987034784252
1961	0.2377603927757786
1962	0.22503747733417062
1963	0.32702229734523197
1964	0.2693909285689231
1965	0.3418797826076151
1966	0.34383261453327535
1967	0.3420781144943432
1968	0.40668964881378256
1969	0.38688906916952087
1970	0.42920050651340247
1971	1.3690657593641038
1972	1.4473712130734007
1973	1.5453041438517436
1974	1.703410708014043
1975	1.8012255567316726
1976	1.9387590533386074
1977	1.9490842654295966
1978	1.9849564578238372
1979	2.1200138342886534
1980	2.2995212123466517
1981	2.515186479880326
1982	2.5887089142379742
1983	2.742843031622767
1984	2.936111534473796
1985	3.042167060229204
1986	3.1054846393621385
1987	3.154027930363114
1988	3.369069329612178
1989	3.3650275013168534
1990	3.338966761700708
1991	3.4131151149040253
1992	3.481921315745642
1993	3.59303458530007
1994	3.669021914795436
1995	3.7458573195723632
1996	3.8705297771333753
1997	3.951681663222945
1998	3.9952631192144796
1999	4.023926999219267
2000	4.159598708278497
2001	4.230826810958046
2002	4.250080676316521
2003	4.215138079746015
2004	4.185084567403761
2005	4.194744469418987
2006	4.2086612367206975
2007	4.190225067227738
2008	4.2851697148472665
2009	4.335912794656158
2010	4.331506887457262
2011	4.412131950442175
2012	4.5731942922782975
2013	4.7644802850818
2014	4.962982931525059
2015	4.10183159497262