Year	% of total fuel combustion
1960	14.73441289212235
1961	14.345961903423069
1962	14.843879341743651
1963	14.524375743162901
1964	14.586322333811575
1965	14.321677617501194
1966	13.650008829242452
1967	13.214063296155807
1968	13.541414071431046
1969	13.27986683816297
1970	13.307030129124819
1971	13.805184770735087
1972	13.704502219403933
1973	13.187364198562593
1974	13.584888617913716
1975	14.778412100523807
1976	15.068430604860342
1977	15.353871773522066
1978	16.519981236178435
1979	16.951683397094246
1980	18.09176884271974
1981	18.194387001477104
1982	18.113626384348926
1983	18.481024920684895
1984	17.757821225898894
1985	18.39579603857481
1986	19.03640059127864
1987	19.616104331454416
1988	19.212453821350017
1989	19.990666804936225
1990	19.194695368056895
1991	20.326737891055426
1992	20.711439954467842
1993	21.215655532398998
1994	21.09641073401448
1995	21.665929423234903
1996	21.982189385016238
1997	22.195305770887167
1998	22.61282004052312
1999	22.13292364527645
2000	21.706214293224914
2001	22.247669914932
2002	21.180255491003052
2003	20.69821831015861
2004	20.31219345758519
2005	19.724540830623177
2006	19.676686683758625
2007	18.716222936905275
2008	19.389612707478136
2009	20.163405475781644
2010	19.264809051824937
2011	18.160450193871597
2012	17.91679420256285
2013	17.547983083929736
2014	17.53699637397676