Year	% of total energy use
1971	1.888519824797684
1972	1.8197530815368825
1973	1.4729914077920394
1974	2.1918420680095854
1975	2.30651044284212
1976	2.3577126097154473
1977	2.6031139726487518
1978	2.7189748458489205
1979	2.8009563458226747
1980	2.805033066548579
1981	2.9230734303496546
1982	2.8261999823423816
1983	2.1282466783128977
1984	3.549599267127548
1985	4.123034867539223
1986	4.407509914814364
1987	3.4925066367550226
1988	4.10747458414813
1989	4.41780983903737
1990	4.059546748094968
1991	3.8857656364768594
1992	3.575438976325535
1993	4.386921391695777
1994	4.942858174311693
1995	5.001536332083128
1996	3.414809248885213
1997	3.479720357840648
1998	3.8284602507197967
1999	3.7306443042912307
2000	2.296456415882572
2001	2.378737773895124
2002	2.0446151301355906
2003	2.3631148525692245
2004	2.147313845394585
2005	2.2022915903064324
2006	3.0994680891473383
2007	2.656580163068127
2008	2.8371384447471093
2009	3.1184992213729505
2010	4.295240303808343
2011	3.335408032419603
2012	2.3127007734971965
2013	5.399516360774808
2014	3.434473519897887