Year	% of total fuel combustion
1960	19.13016846459402
1961	19.370731282899026
1962	19.29703640777954
1963	19.14990239559596
1964	19.22632758121562
1965	18.880299625468165
1966	19.03006300630063
1967	19.153816339525484
1968	19.47199250971592
1969	19.335322393502405
1970	19.028203751399268
1971	19.098690830512016
1972	19.368276456268262
1973	19.399367694628484
1974	19.487900840341098
1975	20.55669797250342
1976	20.33412383704742
1977	20.587181704117285
1978	21.280547762228124
1979	20.93041495010322
1980	21.02779360956764
1981	21.41401455687169
1982	21.948272525538105
1983	22.475876119332266
1984	22.525088212542144
1985	22.54148979428967
1986	23.058426596133415
1987	23.36935790306894
1988	23.776591228971654
1989	24.038313223914834
1990	24.392632311103768
1991	24.427451209308664
1992	25.043975296282454
1993	25.267838194027785
1994	25.64805538236622
1995	25.786889245846975
1996	25.724383598539657
1997	25.8313663983954
1998	26.322274896895006
1999	26.84449324737721
2000	26.426002961291683
2001	26.443315996297837
2002	26.80917590000702
2003	26.66945134877302
2004	26.75799984870262
2005	26.838341952513748
2006	27.092805279729113
2007	27.002166845619335
2008	26.66608701223224
2009	27.31220477209415
2010	26.712971392047105
2011	26.811800540153417
2012	27.298934687296786
2013	27.279321614280477
2014	28.04240136346984