Year	% of total energy use
1971	0.8345804640579794
1972	1.0761751172666223
1973	1.105026261305745
1974	1.3425604648627154
1975	1.3923443074328457
1976	1.4837238667331039
1977	1.5643059145714744
1978	1.4154711498369013
1979	1.5124213794961
1980	1.4142922816242591
1981	1.4219746924925045
1982	1.3526161360582443
1983	1.1813777066444462
1984	1.5344425873290395
1985	1.8003130927142752
1986	2.30449553205481
1987	1.872028903221637
1988	2.3851670635134528
1989	2.4903559141631315
1990	1.780261703411397
1991	1.8731794006270637
1992	1.8876672553407627
1993	1.6293768785508274
1994	1.7925090310176968
1995	1.9121030495475804
1996	1.9478133775464899
1997	1.96566545213494
1998	1.9519424116849402
1999	1.889350754464484
2000	1.9854363740644936
2001	1.8503592545916816
2002	1.9841314985265743
2003	2.010074779243547
2004	2.029010949855933
2005	1.8972546523406888
2006	1.8653570816266005
2007	1.849174156447735
2008	1.914306509429798
2009	1.8959351642946778
2010	1.9244056914808316
2011	1.9948040341889433
2012	1.942018297576087
2013	2.0579268121100376
2014	1.9400300851117278