Year	% of energy use
1971	9.18357827656254
1972	9.45419844939678
1973	14.226956732456253
1974	14.955340234775367
1975	14.743830102227534
1976	16.545056720851832
1977	14.363199389421776
1978	12.843701126430352
1979	11.555825491168227
1980	7.168714953282761
1981	3.3733931866834093
1982	2.6515429580325853
1983	-0.4085007267774236
1984	0.8945090080401066
1985	-2.917303905495488
1986	2.269006043129297
1987	6.381493840111435
1988	3.319582345216835
1989	-1.57735494330777
1990	-5.109711721025554
1991	-5.754620828395495
1992	-8.781367960928065
1993	-14.066630290583158
1994	-17.169829601932758
1995	-24.20044554812046
1996	-29.506467943514586
1997	-32.77603390015788
1998	-32.971480652556664
1999	-32.32027566785396
2000	-34.65256336976124
2001	-45.53510937250454
2002	-45.62212601822805
2003	-41.41718252482141
2004	-29.824428220493953
2005	-26.542802547991517
2006	-18.158819009166315
2007	-12.669946576213889
2008	-6.231592750954216
2009	-7.354513205641347
2010	-1.072041291754964
2011	3.2179091976879697
2012	6.141447960597681
2013	12.688577630341491
2014	13.02936074290009