Year	% of energy use
1971	-0.8798846764887217
1972	5.241638688393447
1973	10.05496837184223
1974	1.2819347551467577
1975	-6.547163082039302
1976	-7.2825820275132385
1977	-15.629319402694072
1978	-24.141398776015066
1979	-35.29230294782028
1980	-54.58561537039203
1981	-68.60432749699446
1982	-84.02560277246234
1983	-93.05377142863424
1984	-86.64091553134183
1985	-77.54313516985641
1986	-72.32119588572884
1987	-71.7389214241362
1988	-68.9485735445891
1989	-62.11397876080246
1990	-58.09692346978282
1991	-57.11082567748672
1992	-55.252071447210746
1993	-54.95049285563965
1994	-50.875767636433075
1995	-54.792244037637936
1996	-59.026718949961634
1997	-59.386941139737296
1998	-55.211967431778305
1999	-49.9585799447031
2000	-51.53968913281013
2001	-50.53612214655898
2002	-51.790161492708265
2003	-52.04619803639039
2004	-52.03506655639575
2005	-44.95931079807592
2006	-42.21934338175325
2007	-36.638312780608764
2008	-26.918941825734183
2009	-24.748011212429493
2010	-22.697887892408712
2011	-18.016270668029367
2012	-13.98153470678494
2013	-12.725915036785587
2014	-10.793600982405087
2015	-4.666485312736533