Year	% of total fuel combustion
1971	13.884228187919463
1972	13.86286490156144
1973	12.840809146877747
1974	12.229359980965976
1975	13.29250311897471
1976	12.570217276099628
1977	12.8374325134973
1978	12.969800246142196
1979	12.855855855855859
1980	12.48335552596538
1981	12.370806169502307
1982	12.039512774806889
1983	12.021238938053097
1984	12.34080841638981
1985	12.409582586767538
1986	12.984025559105431
1987	12.116231288523629
1988	12.017696141569132
1989	13.498832092997988
1990	7.140309155766944
1991	6.7464446756850505
1992	6.9693430656934305
1993	7.037474181174388
1994	7.40718235401349
1995	16.794462511561296
1996	17.457467726767543
1997	18.506484641638224
1998	18.030513176144247
1999	18.385804517191374
2000	17.65422950976408
2001	17.488491400041227
2002	17.578445503936134
2003	16.676874617201857
2004	16.016526152426493
2005	16.00871881811577
2006	15.681680626330074
2007	15.048109196688298
2008	15.60515433466253
2009	14.352008416939091
2010	13.83168065090262
2011	14.414177534707614
2012	14.512232996307667
2013	13.10236274950704
2014	13.134025842411958