Year	% of total fuel combustion
1960	0.005351313747524903
1961	-9.281831118195478E-16
1962	1.738798785630629E-15
1963	1.6369689346175646E-15
1964	-1.5292986435368692E-15
1965	-2.84410493439579E-15
1966	0
1967	2.574243662633506E-15
1968	-0.003373022565523887
1969	0
1970	0.918702370553329
1971	1.0554167279141586
1972	1.0451890562557666
1973	1.7440157627073527
1974	1.959715516793853
1975	1.9202715964246881
1976	1.4853266176697355
1977	1.6860928471807142
1978	1.9799523620484327
1979	1.2487416710608312
1980	1.2269938650306729
1981	1.301249099803818
1982	1.2785601286340431
1983	2.4936010766023684
1984	1.4405275171189467
1985	1.4880272212488272
1986	1.5271727857291038
1987	1.5054848064556798
1988	1.4908229999296763
1989	1.630594567700206
1990	1.7496186117467574
1991	1.7893462469733685
1992	1.8766881972988831
1993	1.9706994328922502
1994	1.9229014598540146
1995	1.9892628812011315
1996	2.0483125189058393
1997	2.067134854945239
1998	1.962443252166735
1999	1.981118725615056
2000	1.9315341844741059
2001	1.7384805994218184
2002	1.5281423155438902
2003	1.5107832859068444
2004	1.5320572525613478
2005	2.360394707333483
2006	2.4631763718232462
2007	2.462965626348338
2008	2.5660863958736297
2009	2.2679930694804056
2010	2.6585528192450325
2011	2.9039060896179745
2012	2.8369322412509312
2013	2.9035603180089877
2014	2.9109589041095902