Year	% of energy use
1971	9.220071493140443
1972	7.495200474543796
1973	8.814704983003882
1974	8.288675128900742
1975	4.237240488739351
1976	3.0015662548219657
1977	4.803974187192853
1978	4.628609518568152
1979	6.619580126232159
1980	5.812768463682684
1981	5.291920303675723
1982	6.492070716821451
1983	6.265724429958973
1984	6.85601039981324
1985	6.084603800303966
1986	6.499382111327733
1987	4.827495804216963
1988	-1.8319620027199555
1989	-5.012534474360551
1990	0.03554999786658974
1991	-3.428671938792894
1992	-4.37872700981218
1993	-7.821374872519268
1994	-13.32660519502438
1995	-11.827085036808544
1996	-10.345054034104882
1997	-9.493421016916313
1998	-8.825818039640568
1999	-10.884148223398574
2000	-14.988869031353875
2001	-15.242020613595095
2002	-16.109742639228624
2003	-15.54105683435826
2004	-11.288499232197065
2005	-9.62902614148868
2006	-8.594029219126748
2007	-7.942883481793853
2008	-5.864230680672849
2009	-6.453627577063363
2010	-8.33640194104776
2011	-7.862019710148224
2012	1.516596302925738
2013	1.3211560863527225
2014	4.966232234198399