Year	% of total energy use
1971	0.9065403519575428
1972	1.1122097372660305
1973	1.157683204669249
1974	1.4530498385841233
1975	1.536082483477877
1976	1.57957289539241
1977	1.6807105851109956
1978	1.5596177929545008
1979	1.6978902752880047
1980	1.669498784363263
1981	1.7144649016738744
1982	1.7375141758454957
1983	1.6024685419772577
1984	1.5899436357387624
1985	1.7149553199625769
1986	1.897501707807223
1987	1.862486825245048
1988	1.857436895831458
1989	1.8497301308768392
1990	1.1939623967884578
1991	1.189131923745861
1992	1.1214200477275573
1993	1.0967648333930515
1994	1.0120825137025555
1995	1.016654878254485
1996	0.9927090471221045
1997	0.9185391688035313
1998	0.978629657752849
1999	0.9647695102912683
2000	1.047147007153156
2001	1.169042652187122
2002	1.243019496146923
2003	1.3401412774676422
2004	1.370993969145647
2005	1.509636778765873
2006	1.52826084333703
2007	1.5249286621537386
2008	1.4466074970693241
2009	1.3945789260543755
2010	1.5113343157210992
2011	1.4588061782538004
2012	1.4979554200844483
2013	1.5084213805021518
2014	1.3471861611120561