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	6.302559315779192
1972	6.208650982544824
1973	6.378940546545901
1974	6.040318298447498
1975	6.053930387437968
1976	5.863115047872613
1977	5.814441208580362
1978	5.761853379527279
1979	6.051364965529017
1980	5.639270666593069
1981	5.799046460257863
1982	5.7432731149437775
1983	5.787949510624519
1984	5.717013398091548
1985	5.477747848842066
1986	5.216906758713997
1987	5.160836817347736
1988	4.98158125106488
1989	4.340071681330478
1990	5.766312255676574
1991	5.6588147879506225
1992	5.056148231330713
1993	5.194797920960659
1994	4.950151849665999
1995	4.18685379944515
1996	3.479187091985265
1997	3.7750590483267428
1998	3.5850846345403147
1999	3.752771706212308
2000	3.0493679637681965
2001	3.0577873233400488
2002	2.970453197926327
2003	2.965771618470746
2004	2.976937019351678
2005	2.911976500427425
2006	2.790714306147553
2007	2.7105144968655788
2008	2.6710728383553803
2009	2.756772346457137
2010	2.5599981863025283
2011	2.328760591586193
2012	2.4444754393806774
2013	2.3937337194642967
2014	2.401722263453079