Year	% of total fuel combustion
1971	4.697986577181208
1972	5.228758169934641
1973	4.790419161676647
1974	5.434782608695652
1975	4.864864864864864
1976	5.1886792452830175
1977	4.21455938697318
1978	2.9787234042553186
1979	2.597402597402598
1980	3.8674033149171274
1981	4.2328042328042335
1982	3.2085561497326194
1983	4.591836734693877
1984	4.4692737430167595
1985	6.077348066298343
1986	4.225352112676058
1987	3.24074074074074
1988	3.125
1989	3.508771929824562
1990	4.347826086956521
1991	2.197802197802197
1992	1.886792452830189
1993	1.913875598086125
1994	1.6736401673640169
1995	0.7968127490039842
1996	0.7518796992481205
1997	0.6993006993006995
1998	0.5952380952380953
1999	0.8849557522123898
2000	0.56497175141243
2001	0.539083557951483
2002	0.2610966057441248
2003	0.5063291139240508
2004	0.7317073170731708
2005	0.7444168734491308
2006	0.7075471698113214
2007	2.064220183486239
2008	3.341288782816229
2009	0.47961630695443686
2010	0.4672897196261686
2011	0.4474272930648774
2012	0.6772009029345366
2013	0.7042253521126767
2014	0.8810572687224677