Year	% of total energy use
1960	0.8061091873266525
1961	1.0026897227851863
1962	0.8154736857379168
1963	1.4806813793121174
1964	1.105815086661768
1965	1.409250236588663
1966	1.373220706346643
1967	1.3493500040400082
1968	1.7038788894443258
1969	1.7495392460005037
1970	1.5558481892071114
1971	1.4374699048220516
1972	1.5177809157637159
1973	1.6281824618418979
1974	1.7983475413413401
1975	1.9032705940790366
1976	2.0659674854476773
1977	2.0604524985053074
1978	2.093202496645645
1979	2.2331791581873066
1980	2.3836489401136536
1981	2.5814524056351003
1982	2.649356512431099
1983	2.7744827730292223
1984	2.9474034207244078
1985	3.0479930497564283
1986	3.1337531919869996
1987	3.1477553676825205
1988	3.3469962553374786
1989	3.3521698540544116
1990	3.2939304891381074
1991	3.325634137132843
1992	3.394424980112077
1993	3.4886930543092523
1994	3.557108961718714
1995	3.622680512610105
1996	3.7278411997366847
1997	3.7486543686621503
1998	3.769328676856224
1999	3.790016069005277
2000	3.9176624166956944
2001	3.9900511742955764
2002	4.0142851570150855
2003	4.015676794606645
2004	3.9813199030356223
2005	3.9860320873476915
2006	4.010829098063654
2007	3.9929945826774698
2008	4.068946851307118
2009	4.109876397015536
2010	4.13710433037939
2011	4.224560555492619
2012	4.387722334417873
2013	4.5612814394177805
2014	4.778067173387208
2015	4.800517915255666