Year	% of total fuel combustion
1960	1.6664258536820309
1961	1.7585374907201208
1962	1.6548360405870335
1963	1.8312510696559978
1964	1.8286182861828626
1965	1.8602630435641216
1966	1.8901718684501352
1967	1.9426728245729799
1968	1.996357523115717
1969	2.0338763480908124
1970	2.13360985419809
1971	6.306931979586259
1972	6.2235475995370555
1973	6.393148378829065
1974	6.050187619058572
1975	6.065398813793587
1976	5.873734990645448
1977	5.814306431486291
1978	5.770890365942174
1979	6.061180947353371
1980	5.640523177387967
1981	5.825882251306639
1982	5.761913105789374
1983	5.7772040397904165
1984	5.701428413880404
1985	5.478786065558443
1986	5.198603112473686
1987	5.088039835458555
1988	4.908434869430397
1989	4.277290186400713
1990	4.980503449925568
1991	4.864132184278053
1992	4.352116788321167
1993	4.502404433939197
1994	4.288671050882079
1995	4.0930639648822025
1996	3.3979181133501344
1997	3.7234371548486855
1998	3.482540148994823
1999	3.67539916974454
2000	2.956463101465933
2001	2.960100972664904
2002	2.892775704654947
2003	2.897821968217081
2004	2.9140632872056407
2005	2.850700787370373
2006	2.7148733427810616
2007	2.6274858271582895
2008	2.5937977199391895
2009	2.7205146826628934
2010	2.5070447210241125
2011	2.2754759601927894
2012	2.3811090289530883
2013	2.3178584878259416
2014	2.3288639500025514