Year	% of total fuel combustion
1971	5.826935155158491
1972	6.028603389585864
1973	6.296433448283843
1974	6.673471702393104
1975	6.4024716066414715
1976	6.244749369924392
1977	6.110249983510322
1978	5.877035676274621
1979	5.9943845173120165
1980	5.795571198122892
1981	5.88599523813034
1982	5.943073842692495
1983	5.998814782889775
1984	5.880245365422749
1985	6.024518819701172
1986	6.21306967764582
1987	6.072013987542345
1988	5.970777311350408
1989	5.989968553767181
1990	5.155736678324036
1991	5.2268934458084715
1992	5.491394083898368
1993	5.656878519710378
1994	5.044321029671113
1995	4.876899843440432
1996	6.569432016406171
1997	5.698754558590793
1998	5.386889978631125
1999	6.151119325783803
2000	8.538331929233362
2001	8.317451506460666
2002	8.364738512566836
2003	8.172490882441483
2004	8.19775539665807
2005	7.710210168175599
2006	7.610673648036151
2007	7.457135039119929
2008	7.872612158923081
2009	7.539341978107686
2010	7.543742417656561
2011	7.496869462492617
2012	8.099088617638156
2013	8.3861275770254
2014	8.59869527322669