Year	% of total fuel combustion
1960	19.172690319851387
1961	19.413947217658936
1962	19.34073748359659
1963	19.191656056555416
1964	19.271075043586237
1965	18.93076484410222
1966	19.08391909338689
1967	19.20005845228281
1968	19.513929312304906
1969	19.367063663123666
1970	19.06247911567115
1971	18.864577900240057
1972	19.11478060743509
1973	19.186480519686793
1974	19.304679783786554
1975	20.040623813792713
1976	19.82815335839748
1977	19.904093169161584
1978	20.385902126251523
1979	20.097227341549186
1980	20.177159135841645
1981	20.50817507490007
1982	20.732669794361378
1983	20.962890996568362
1984	20.82590052718395
1985	20.8439665544498
1986	21.146309212626136
1987	21.235871286035124
1988	21.477696309083974
1989	21.65974882632162
1990	19.991107512891336
1991	20.069744587398844
1992	20.515548677274268
1993	20.63221438267442
1994	20.89895340393102
1995	20.859077012665598
1996	21.31230261129196
1997	21.29792707198918
1998	21.625783120946128
1999	22.081332501649975
2000	22.021792719730517
2001	21.94081876454042
2002	22.03576201070693
2003	21.604600823288568
2004	21.446485231153467
2005	21.063985401499167
2006	20.771813946787233
2007	20.556165822391037
2008	20.436152291526273
2009	20.411518434119454
2010	20.004470188660417
2011	19.746031198221566
2012	20.13163054951695
2013	20.15185501621638
2014	20.4490615718503