Year	% of total fuel combustion
1960	9.531129900076865
1961	8.267716535433072
1962	9.01386748844376
1963	9.51714485654304
1964	9.324324324324325
1965	8.915211970074813
1966	8.79424778761062
1967	7.8761542639869635
1968	8.969759097898512
1969	9.880514705882351
1970	11.152882205513784
1971	9.917355371900829
1972	8.832271762208066
1973	6.849315068493151
1974	5.15645658880564
1975	5.423728813559322
1976	19.968429360694557
1977	19.37547027840482
1978	18.500738552437223
1979	18.756512678013202
1980	17.517443995593094
1981	16.33935585231736
1982	14.802631578947366
1983	13.278688524590166
1984	11.89620758483034
1985	12.381673608481636
1986	11.61225176708179
1987	12.91258614435981
1988	11.611972592859718
1989	10.262089331856775
1990	9.031318281136198
1991	7.745664739884392
1992	6.412478336221837
1993	5.897771952817825
1994	5.854873871068203
1995	5.891719745222931
1996	7.138442521631644
1997	5.74611550864849
1998	5.230769230769231
1999	5.321150228433217
2000	4.706620646375901
2001	5.626520681265207
2002	6.646153846153846
2003	5.961209355390758
2004	4.749859471613266
2005	4.059147579008408
2006	4.174894217207334
2007	3.746877601998335
2008	3.4277620396600565
2009	3.616484440706476
2010	3.6987759446514104
2011	3.2053053329649077
2012	2.9361942405420662
2013	2.9914529914529915
2014	2.463891248937978