Year	% of total energy use
1960	2.727827716374737
1961	2.8005600970759144
1962	2.7646641274614474
1963	2.7732031924972764
1964	2.7787836585195107
1965	2.9818181048177137
1966	3.0748113304328952
1967	3.0543203511070476
1968	3.0518646445875874
1969	3.0664227830015465
1970	2.986153445386814
1971	3.1744584182835553
1972	3.428040053032915
1973	3.596702134768528
1974	4.25685161158636
1975	5.044694460640455
1976	5.005688694980944
1977	5.52607650422742
1978	6.036806871385509
1979	6.121075008263032
1980	6.55500873828046
1981	7.504670540695302
1982	8.115523085809444
1983	8.91076337777931
1984	9.736527055383272
1985	10.829016207403448
1986	11.511136473919272
1987	11.775967098530925
1988	12.164023085507932
1989	12.315601293524896
1990	12.070254845854816
1991	12.519537485090364
1992	12.49583334583755
1993	12.787070031008257
1994	12.846837196352007
1995	13.133255637643181
1996	13.14068643861975
1997	12.872621494132504
1998	13.0813804497594
1999	13.28918848087284
2000	13.208756274008984
2001	13.321744103421699
2002	13.354347824323035
2003	12.983109623648005
2004	13.264011775225304
2005	13.295650572539257
2006	13.419095751033408
2007	13.004964571979782
2008	13.301855032853602
2009	13.790181634753472
2010	13.646016430793976
2011	13.12294810411372
2012	12.690080559322626
2013	12.898728823510071
2014	13.201246978383741
2015	13.354082784059232