Year	% of total energy use
1971	0.8345804640579794
1972	1.076175117266622
1973	1.1050262613057449
1974	1.3425604648627152
1975	1.3923443074328459
1976	1.4837238667331036
1977	1.5643059145714744
1978	1.4154711498369013
1979	1.5124213794960994
1980	1.4142922816242587
1981	1.4219746924925045
1982	1.3526161360582443
1983	1.1813777066444457
1984	1.5344425873290397
1985	1.8003130927142756
1986	2.3044955320548106
1987	1.8720289032216364
1988	2.3851670635134528
1989	2.490355914163131
1990	1.7802617034113972
1991	1.8731794006270632
1992	1.8876672553407619
1993	1.6293768785508274
1994	1.7925090310176972
1995	1.91210304954758
1996	1.9478133775464894
1997	1.9656654521349388
1998	1.9519424116849402
1999	1.8893507544644839
2000	1.9854363740644936
2001	1.8503592545916812
2002	1.9841314985265746
2003	2.010074779243547
2004	2.0290109498559334
2005	1.897254652340689
2006	1.8653570816266007
2007	1.8491741564477355
2008	1.9143065094297982
2009	1.895935164294678
2010	1.924405691480833
2011	1.994804034188943
2012	1.9420182975760871
2013	2.0579268121100376
2014	1.940030085111728