Year	% of total energy use
1971	1.9694339543641273
1972	1.8150260679161825
1973	1.58995378041336
1974	1.4312297297431695
1975	1.191961191961192
1976	2.1095703940266426
1977	1.2038003697720128
1978	1.9153044149826233
1979	2.051336416522004
1980	1.3971696745352813
1981	3.308354127450514
1982	1.9860829785181815
1983	2.0953025721627494
1984	2.4402050345132573
1985	2.9052235200735166
1986	3.3908334049263176
1987	3.3153006360625645
1988	3.7225100893402425
1989	1.0843548482344787
1990	0.6274968055932629
1991	0.9393893971809437
1992	0.6958038760601944
1993	1.5207912693230825
1994	0.6238667046156445
1995	0.6676451519953898
1996	0.9923024072299976
1997	0.6367711463641871
1998	1.3364652329800157
1999	1.9215874090899616
2000	1.2176429328485843
2001	1.03406460710905
2002	1.251926955247997
2003	1.836001750123389
2004	2.3606115570805106
2005	2.5706573339600127
2006	2.331703171469555
2007	2.183880986249082
2008	1.8093852103818013
2009	1.9370757177241504
2010	1.82806730648178
2011	1.9925938473270417
2012	2.370973166898279
2013	2.9958852962078715
2014	2.343656954981423