Year	% of total fuel combustion
1971	19.960079840319363
1972	20.461606746560143
1973	21.65297245045916
1974	21.861656703672075
1975	18.107156824403596
1976	17.593833780160857
1977	18.787120975304784
1978	19.125683060109292
1979	18.602091359383596
1980	20.157132334888292
1981	19.523707358935848
1982	17.99761620977354
1983	18.209273405578255
1984	18.507124352331605
1985	18.99146625290923
1986	18.684330744632252
1987	18.152281395677353
1988	19.28363182007497
1989	19.69376979936642
1990	20.7503533341899
1991	21.88268807458241
1992	21.93081054077682
1993	22.32131948686622
1994	26.04735883424408
1995	25.988977342314755
1996	26.07938718662953
1997	25.86262495969042
1998	27.257883457495662
1999	27.736512900703676
2000	29.325042623608468
2001	25.276106671455505
2002	25.647599681725758
2003	26.085845682166582
2004	24.45363721511083
2005	21.283363296916054
2006	21.987773614671667
2007	22.633895818048426
2008	22.850453614281534
2009	23.946568824170157
2010	25.413832199546484
2011	25.596802452912836
2012	26.884674309260927
2013	23.34514690751115
2014	22.548623535522594