Year	% of total energy use
1971	0.8345804640579796
1972	1.076175117266622
1973	1.1050262613057449
1974	1.3425604648627152
1975	1.3923443074328457
1976	1.4837238667331039
1977	1.5643059145714744
1978	1.4154711498369015
1979	1.5124213794961001
1980	1.4142922816242587
1981	1.4219746924925043
1982	1.3526161360582438
1983	1.181377706644446
1984	1.5344425873290402
1985	1.800313092714275
1986	2.30449553205481
1987	1.8720289032216375
1988	2.385167063513453
1989	2.4903559141631315
1990	1.780261703411397
1991	1.8731794006270632
1992	1.8876672553407623
1993	1.6293768785508271
1994	1.7925090310176968
1995	1.91210304954758
1996	1.9478133775464899
1997	1.9656654521349393
1998	1.9519424116849395
1999	1.8893507544644845
2000	1.985436374064494
2001	1.850359254591681
2002	1.9841314985265743
2003	2.0100747792435474
2004	2.029010949855933
2005	1.8972546523406884
2006	1.865357081626601
2007	1.8491741564477355
2008	1.914306509429798
2009	1.8959351642946778
2010	1.924405691480832
2011	1.9948040341889426
2012	1.9420182975760862
2013	2.0579268121100376
2014	1.940030085111728