Year	% of total energy use
1971	1.4981931266826958
1972	1.8403841266869072
1973	2.0927949936688783
1974	2.2959997543814215
1975	2.3455642081967465
1976	2.3191879845687104
1977	2.3793343479748463
1978	3.1999493915483885
1979	3.545004861962542
1980	3.5953984545325266
1981	3.796590994025448
1982	3.6142441636633245
1983	3.6205133037373867
1984	3.723513608975588
1985	5.608149130894291
1986	5.980545986331349
1987	6.939850349921035
1988	7.204131309181124
1989	7.260238420532771
1990	6.3931535673387065
1991	6.245983871915161
1992	5.450686568690422
1993	5.373586362041082
1994	4.18235289466967
1995	3.712817122452362
1996	4.7326477219784175
1997	4.5986490784151846
1998	3.994611586064293
1999	5.132666039824863
2000	5.697521503086294
2001	4.401937203565568
2002	3.567157969447375
2003	3.454500587692234
2004	2.524781902816546
2005	2.741540714967852
2006	3.2974497252985966
2007	3.1435658801004496
2008	3.342621321485436
2009	4.103438182164532
2010	4.367479693500694
2011	3.547945974029259
2012	3.5965266756469805
2013	3.4072236232127113
2014	3.3279517054850305