Year	% of total energy use
1971	0
1972	0
1973	0.9391542218782571
1974	1.1787933131474078
1975	1.0598186280623212
1976	1.2557196403291677
1977	0.9476653417515193
1978	1.2032237190005057
1979	3.7043735722800606
1980	9.317299230751216
1981	11.993596073323406
1982	14.561948356342636
1983	15.290437218797678
1984	19.229762341038686
1985	19.841627076030772
1986	18.734477749094015
1987	17.50334601144404
1988	17.902709555517752
1989	18.563483656900235
1990	2.7826240295443947
1991	2.7272859819635493
1992	2.3217776421096263
1993	2.4509429917708236
1994	2.6347332222697464
1995	2.5059753206036404
1996	2.670830328792814
1997	2.5370654260343573
1998	2.6222457218090223
1999	3.380500713973724
2000	3.3715396383505123
2001	3.2783118466982217
2002	3.0502304172397863
2003	3.1551468848339272
2004	3.296251468733233
2005	3.2351283625897307
2006	3.669149095430059
2007	3.3758965975627593
2008	3.5787050944722507
2009	3.7351788556437824
2010	3.091876914244614
2011	3.3872963494474106
2012	3.3250829360337346
2013	3.0970933403740393
2014	2.9063614903880524