Year	% of energy use
1960	16.716146904005498
1961	17.635803486572122
1962	19.022630300247688
1963	21.14044162201755
1964	21.961508102703327
1965	23.6913398578209
1966	24.519813302689343
1967	24.685404332633833
1968	26.671127049509934
1969	29.32678481632514
1970	29.5000190919107
1971	-3.6765976763699046
1972	-3.2302260033949635
1973	-3.4145486871004005
1974	-3.566624925475575
1975	-2.141647041834996
1976	-1.5475857056622824
1977	-1.6803498678447781
1978	0.44999708349033446
1979	-1.4731767948732244
1980	-0.8618498912646212
1981	0.2253332051697038
1982	1.0387663363910158
1983	2.007784823518477
1984	0.6798631253199625
1985	1.6780896225293114
1986	0.7004224589827999
1987	1.7096100724086019
1988	1.4032116360944227
1989	1.0028918484661802
1990	-2.8905382749209063
1991	-2.400361275200787
1992	-3.050104903855786
1993	-2.3372147601187345
1994	-3.134376633180178
1995	-3.046401781134184
1996	-2.952860297782094
1997	-3.3376896508886147
1998	-4.061710565726634
1999	-2.114766839759151
2000	-2.8029489530745737
2001	-3.2675664582432513
2002	-1.9438499552447102
2003	-2.4335994367622176
2004	-2.7325007780543165
2005	-3.198112732659961
2006	-3.1630154941737834
2007	-2.2022056284062854
2008	-2.957010330346648
2009	-2.891887649415407
2010	-2.0950109169654723
2011	-3.129742466536586
2012	-2.73341295388368
2013	-3.067184776668436
2014	-2.459859394382207
2015	20.96904249832592