Year	% of total fuel combustion
1971	0
1972	0
1973	6.557377049180328
1974	8.928571428571429
1975	7.894736842105263
1976	5.128205128205128
1977	4.545454545454545
1978	3.4482758620689653
1979	3.7593984962406015
1980	4.651162790697675
1981	3.7037037037037033
1982	17.045454545454543
1983	14.285714285714285
1984	20.52980132450331
1985	19.04761904761905
1986	18.243243243243246
1987	17.96875
1988	18.055555555555557
1989	9.734513274336285
1990	13.186813186813188
1991	12.149532710280374
1992	11.711711711711711
1993	10.833333333333334
1994	13.793103448275865
1995	12.977099236641221
1996	12.056737588652485
1997	11.842105263157894
1998	10.493827160493826
1999	11.184210526315788
2000	10.273972602739729
2001	10.135135135135137
2002	12.318840579710145
2003	11.510791366906476
2004	11.18881118881119
2005	9.826589595375722
2006	9.444444444444443
2007	10.309278350515465
2008	9.5
2009	9.223300970873787
2010	10.526315789473685
2011	9.364548494983278
2012	9.46372239747634
2013	9.43952802359882
2014	8.882521489971346