Year	% of total fuel combustion
1960	15.783608550298855
1961	20.03699136868064
1962	21.86833282535812
1963	19.433754810335348
1964	23.4670704012112
1965	23.28862973760933
1966	24.49546182594768
1967	26.310474175242867
1968	26.254843254667136
1969	27.006022135416668
1970	25.46156367211682
1971	26.183892153473902
1972	26.377965603889958
1973	28.17111842907672
1974	29.44976004346383
1975	29.18848993500347
1976	31.00482667836771
1977	30.71856107317953
1978	31.911873428951647
1979	32.05483323911814
1980	33.894487922977305
1981	34.49960963479166
1982	34.87962935812099
1983	34.64477949266958
1984	33.489338052476086
1985	33.515631854473135
1986	34.338665967304834
1987	35.312612041148405
1988	35.31497136623943
1989	36.06156726119286
1990	36.83886048960929
1991	35.79302529232989
1992	35.83169138234989
1993	35.23540784867012
1994	36.323272900259
1995	37.40585565364856
1996	36.52145513013767
1997	36.795792202612425
1998	36.792888198003446
1999	35.29454022988505
2000	36.36363636363637
2001	35.51397419416274
2002	37.196178522924185
2003	36.94201693887179
2004	39.19055575096729
2005	38.94282395739738
2006	40.00801674609183
2007	40.65119862237731
2008	40.46974856556422
2009	38.40619379056854
2010	39.0645334149889
2011	39.5744902476498
2012	39.279284194445964
2013	36.326458036984356
2014	35.56035156860906