Year	% of energy use
1971	11.487056136642494
1972	8.568364620126996
1973	5.497026072657704
1974	4.939224441523501
1975	5.724002260477798
1976	3.8535860697246367
1977	5.447571684541005
1978	4.716743836012722
1979	1.8257270587321481
1980	-0.4963551762171411
1981	-4.274998273510919
1982	-6.473759155447639
1983	-8.280505266327369
1984	-12.397491386670792
1985	-12.355747701390204
1986	-11.595732420999324
1987	-10.916374184987584
1988	-10.081895539594589
1989	-9.50769668798064
1990	-8.469523757481497
1991	-8.443763580838029
1992	-8.409630637268279
1993	-8.793134880492318
1994	-7.606843204811829
1995	-5.8133990775778575
1996	-6.489681307833401
1997	-6.92671103360722
1998	-7.82819313608552
1999	-8.508722936483787
2000	-14.098732210955625
2001	-14.234664550222945
2002	-13.846591187139342
2003	-13.84044717001859
2004	-16.33147228225226
2005	-18.072734045039788
2006	-19.60591925493171
2007	-20.68261097552767
2008	-19.811200809738104
2009	-18.615419349470752
2010	-18.520618264098424
2011	-18.388824771431285
2012	-9.96573940413953
2013	-9.815368057877098
2014	-10.781255269245877