Year	% of total fuel combustion
1971	32.94460641399417
1972	32.00412512891028
1973	34.00454693082169
1974	33.40736040609137
1975	32.41994057444701
1976	34.4120474206985
1977	32.42550464594681
1978	29.00153609831029
1979	27.38306690349319
1980	27.140156629759655
1981	26.794657762938233
1982	25.565168852916553
1983	23.185648273987496
1984	23.21525885558583
1985	21.170830179157207
1986	21.309090909090912
1987	19.774565057583924
1988	18.38369963369963
1989	18.237426370638875
1990	20.71583514099783
1991	17.9137323943662
1992	16.720464816010328
1993	16.026058631921824
1994	16.109544905356426
1995	17.148262813897492
1996	15.592549859897808
1997	16.94992412746586
1998	15.126300148588413
1999	16.306888491681566
2000	18.33788529067499
2001	18.217609162491055
2002	16.859279401767505
2003	17.93004410708791
2004	15.663580246913579
2005	15.988265493215986
2006	15.457656116338754
2007	16.14242375858215
2008	16.14508709750396
2009	16.51401803817381
2010	17.53399581589958
2011	17.2967505373625
2012	17.404444444444444
2013	16.669362229769803
2014	16.57314629258517