Year	% of total fuel combustion
1971	32.746085011185684
1972	33.917175831636115
1973	33.82334464128659
1974	33.131096835593624
1975	33.53748440512646
1976	34.42501324854266
1977	36.112777444511096
1978	37.76389283347533
1979	37.072072072072075
1980	38.28229027962716
1981	37.573541103514074
1982	36.950386215092095
1983	36.31858407079646
1984	35.42358803986711
1985	34.879554051363726
1986	34.35143769968051
1987	32.17493395949515
1988	32.77146217169737
1989	32.96757021022326
1990	21.860879904875148
1991	22.673141403630474
1992	23.59708029197081
1993	22.862201239303626
1994	22.926414291790724
1995	25.061908882059853
1996	27.02687298737568
1997	27.781569965870304
1998	26.393383674937066
1999	25.989825259898254
2000	26.041542175586205
2001	26.42970020383391
2002	26.535092582326197
2003	27.080234491206582
2004	27.565957803783395
2005	26.935496891902805
2006	25.74630508209844
2007	25.967778026404112
2008	26.672574213557812
2009	28.209897418554842
2010	28.616831934909733
2011	28.332281587435148
2012	28.736326305255528
2013	29.7488497595738
2014	29.75255468288151