Year	% of total fuel combustion
1971	8.96551724137931
1972	9.170305676855897
1973	10.48689138576779
1974	11.749347258485642
1975	14.504881450488147
1976	13.157894736842103
1977	15.629522431259046
1978	13.154172560113153
1979	13.53276353276353
1980	13.048933500627353
1981	8.553459119496855
1982	11.082474226804123
1983	11.610486891385767
1984	10.120481927710841
1985	10.071942446043165
1986	9.332113449222325
1987	8.472222222222221
1988	7.8403421240199584
1989	6.106870229007633
1990	8.984615384615385
1991	9.197324414715718
1992	8.61878453038674
1993	11.277744451109777
1994	13.788659793814434
1995	13.452617627567925
1996	16.816608996539795
1997	17.04035874439462
1998	16.960352422907494
1999	15.379623621025306
2000	15.876598946576372
2001	11.643330876934414
2002	11.111111111111112
2003	13.286713286713287
2004	7.836990595611285
2005	9.250243427458617
2006	17.05020920502092
2007	19.85446985446986
2008	22.684563758389263
2009	26.6016713091922
2010	14.951245937161428
2011	9.66576332429991
2012	9.527972027972027
2013	8.16326530612245
2014	7.5718015665796345