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	1.3448658686982446
1972	1.4404227905770637
1973	1.5382947538721783
1974	1.707722383502769
1975	1.807055291508884
1976	1.9470016151408072
1977	1.9591257772453046
1978	1.986980940327394
1979	2.123864876350517
1980	2.2773663171149345
1981	2.473921324602993
1982	2.5367775829163604
1983	2.6646795768806735
1984	2.8494809812341124
1985	2.9537907916201194
1986	3.027161514503207
1987	3.058422787329411
1988	3.2585121025604162
1989	3.261847769435818
1990	3.235251702053102
1991	3.299899714579046
1992	3.364136005707188
1993	3.4558907465946365
1994	3.524786080148381
1995	3.5903350258844564
1996	3.6944303262787157
1997	3.7549702087823014
1998	3.7736668262464232
1999	3.799967302095108
2000	3.936909243285693
2001	4.003190170393679
2002	4.021347744508117
2003	4.011359845521691
2004	3.995209676049143
2005	4.010746257678298
2006	4.028850507072875
2007	4.00901813657823
2008	4.095126642338517
2009	4.148472841209583
2010	4.164600975532902
2011	4.244018240443662
2012	4.397712522796659
2013	4.5839680816293225
2014	4.7826681025306055
2015	4.10183159497262