Year	% of total fuel combustion
1960	29.059829059829063
1961	31.30434782608696
1962	29.032258064516125
1963	29.92125984251969
1964	31.007751937984494
1965	30.000000000000004
1966	29.333333333333332
1967	32.3943661971831
1968	32.21476510067114
1969	37.59398496240601
1970	38.63636363636363
1971	5.343511450381679
1972	4.962995211144973
1973	4.746494066882416
1974	4.5775958317826575
1975	4.496340188218891
1976	4.555084745762712
1977	4.060913705583757
1978	3.937250076899415
1979	3.3691959229898076
1980	3.3026529507309146
1981	2.4801348422826877
1982	3.157894736842105
1983	2.777777777777778
1984	2.9175281415116014
1985	3.2265498962894674
1986	2.787456445993031
1987	2.834179357021996
1988	2.900580116023205
1989	2.664129400570885
1990	3.1395091753261113
1991	3.085867620751342
1992	2.5649994170455868
1993	2.545934910532004
1994	2.6181732022272244
1995	2.5786609888810035
1996	2.693221681566142
1997	2.713347921225383
1998	2.828389830508474
1999	2.293958895578161
2000	2.781754960114543
2001	2.737315475608564
2002	2.5051029875672666
2003	2.2668727460072127
2004	2.178085621296837
2005	2.187092318317857
2006	2.1037078730739465
2007	1.9237018262169363
2008	1.9605338782808612
2009	1.9475851251552188
2010	1.7882947976878614
2011	1.7391810144253141
2012	1.7139677239844187
2013	1.7253351850862666
2014	1.601689241386414