Year	% of total fuel combustion
1971	24.61859434085278
1972	23.891206015390942
1973	23.791997476208
1974	24.388726733336522
1975	24.29004569329974
1976	23.741553412800847
1977	23.728984194100473
1978	23.3273219116321
1979	25.738675338533064
1980	26.32703788881919
1981	26.593439598395296
1982	25.972084716479337
1983	23.343693480131346
1984	19.41735967623504
1985	19.587093423359086
1986	19.16163891558104
1987	19.54746185771043
1988	19.10815540777039
1989	20.084007057646225
1990	21.13897320839382
1991	22.401327638552978
1992	21.124557503910427
1993	19.170075978959673
1994	18.769404170295612
1995	19.353678637430697
1996	18.96217965386727
1997	18.18073591091412
1998	18.40692640692641
1999	18.67376844913217
2000	17.85747531078371
2001	18.1497186399069
2002	17.779902110737225
2003	17.33691060284897
2004	16.548919309867717
2005	17.039405010438415
2006	17.113658283255432
2007	18.56931518798588
2008	18.61410926894403
2009	18.057161121913538
2010	19.255218799983595
2011	19.14604541503911
2012	19.013201037835373
2013	18.748096895538893
2014	18.390571297123216