Year	% of total fuel combustion
1971	10.95960895291999
1972	11.348600508905852
1973	12.005856515373353
1974	11.589008363201911
1975	9.754402224281742
1976	9.679633867276888
1977	9.423161602818142
1978	9.159099881563364
1979	9.542280837858804
1980	7.383512544802868
1981	7.805325987144168
1982	7.456472369417108
1983	6.163474303053291
1984	6.118336691701776
1985	6.135194709772226
1986	6.671823631792691
1987	6.6890881913303435
1988	6.829896907216495
1989	7.024408421837153
1990	7.459420025533467
1991	7.069864442127216
1992	7.924107142857142
1993	6.789838337182448
1994	8.253264350825326
1995	9.194565744784086
1996	8.568646543330088
1997	10.009741841207989
1998	10.535624052551794
1999	10.919392222508371
2000	11.00867678958785
2001	14.293361884368307
2002	16.64407698563296
2003	15.053475935828878
2004	16.376691521679092
2005	17.47651006711409
2006	16.753496024129422
2007	18.74474642757075
2008	20.69452286843591
2009	19.38650306748466
2010	20.68865740740741
2011	21.674277016742767
2012	20.710627400768246
2013	20.358716173694148
2014	20.66143879986362