Year	% of total fuel combustion
1960	18.01281125078264
1961	18.11896807720861
1962	18.717066585376475
1963	18.800273831935648
1964	18.347683476834764
1965	18.68557210000395
1966	19.080827712358523
1967	19.518363756322852
1968	18.905855982067806
1969	18.17210221200246
1970	17.75075414781297
1971	22.299344999511195
1972	21.582385676264217
1973	21.040084760727527
1974	21.07853223593964
1975	22.64539455550691
1976	23.24986374371707
1977	23.904428735248434
1978	23.989674811182887
1979	23.65890176295237
1980	25.423527235245924
1981	24.39969552280119
1982	23.53581685290795
1983	23.502217443891954
1984	23.86034255599473
1985	21.316842953432158
1986	20.863632394945927
1987	20.640679827178765
1988	22.167720369159223
1989	22.63547978711636
1990	17.15024490836317
1991	16.42791187871336
1992	15.886648077297192
1993	14.668100868426103
1994	13.870460921338903
1995	16.679611399131407
1996	15.916501861907944
1997	15.912226666480842
1998	15.181288953296791
1999	14.599886340485309
2000	15.27821760578743
2001	14.866586440905257
2002	15.03629608058467
2003	14.868209004538004
2004	15.20444701419109
2005	14.381103300692102
2006	13.77614414601467
2007	14.728672266760356
2008	14.25504589466262
2009	13.402456837719404
2010	13.842401488751545
2011	14.132937244708502
2012	13.616689069440204
2013	13.900031102004956
2014	13.518304790476918