Year	% of energy use
1971	-4.399098924506079
1972	-5.999464528724166
1973	-7.846461563903968
1974	-8.592643296893463
1975	-8.037433123409416
1976	-9.529202893281528
1977	-9.840244390099059
1978	-9.240407069744151
1979	-9.811862641582868
1980	-9.590019560604862
1981	-9.659806520566152
1982	-8.89607376537515
1983	-10.209577162911222
1984	-13.555826230850629
1985	-13.505320671899934
1986	-12.951904760744819
1987	-10.412552162676967
1988	-8.976463471903378
1989	-11.790587534935952
1990	-7.264610381892537
1991	-10.854389979787442
1992	-9.128381425483482
1993	-6.017642887881979
1994	-7.228760893887681
1995	-6.652441823973705
1996	-6.412088850015679
1997	-5.56452950540941
1998	-6.090573331079588
1999	-4.246920665343888
2000	-4.541570360472804
2001	-5.15381147829976
2002	-3.1190858752351
2003	-1.5714331768062588
2004	0.02532781298579502
2005	0.6256997863359134
2006	1.3261736385097405
2007	2.2907260259854945
2008	2.499667590567109
2009	3.8623237865355975
2010	4.895670128871174
2011	4.15975850459126
2012	6.470391759111831
2013	6.907185508916209
2014	7.974699377838891