Year	% of energy use
1971	3.5638457159137067
1972	1.4126154598343441
1973	0.751618927851523
1974	0.24907011100767876
1975	0.05383967360283106
1976	-1.0071927816499582
1977	-0.3823579391983279
1978	1.1591653276806193
1979	0.3116856184142205
1980	1.0727466807148045
1981	1.5112444270214984
1982	1.5082386770770042
1983	-0.799374357013703
1984	-2.534658095729513
1985	-4.009977626601452
1986	-6.241383008368382
1987	-10.012077098265806
1988	-19.74091930753315
1989	-20.122349130875737
1990	-20.20786736450828
1991	-21.834085920296836
1992	-21.90049258123548
1993	-21.546021053879894
1994	-26.958683850878945
1995	-25.951368556382253
1996	-27.45188034432387
1997	-27.54730364415711
1998	-28.7036562758425
1999	-30.61239944315015
2000	-35.801465213097565
2001	-34.27345441437764
2002	-38.45131062935581
2003	-36.647171503756624
2004	-39.999828679805674
2005	-47.22735828677448
2006	-49.32073313320704
2007	-57.320639177106955
2008	-58.58385230410533
2009	-52.93959345316951
2010	-51.03188418929372
2011	-45.48611061761318
2012	-37.30496468995523
2013	-37.41727379962136
2014	-33.48756623127319