Year	% of total fuel combustion
1971	24.176892931720012
1972	24.807321772639696
1973	24.723783679007564
1974	23.70318149773725
1975	22.437936213446417
1976	22.181645621853594
1977	23.800912093096397
1978	23.822918390234033
1979	23.94214011850819
1980	24.901099271080582
1981	24.877420218551805
1982	25.63501625707637
1983	25.93980540104526
1984	26.739320974383567
1985	26.898899094521536
1986	29.58728084503975
1987	28.746026771724043
1988	29.74578633143125
1989	29.21939570731986
1990	28.443623350741174
1991	29.612337889940417
1992	29.86451506306108
1993	29.701546689600494
1994	29.889653776068034
1995	29.63887750158387
1996	29.182042543189567
1997	29.93514255356827
1998	31.49525383507077
1999	31.472993523550244
2000	32.533888409402444
2001	32.94031400818621
2002	32.82241659886086
2003	33.6967482353411
2004	32.85333840593494
2005	33.31232681204415
2006	32.49239465015391
2007	32.444031309454516
2008	32.19759769920487
2009	33.564359012170044
2010	33.1039525531137
2011	32.21321875316224
2012	33.52355283861205
2013	33.955370152587626
2014	34.662122645255856