Year	% of total fuel combustion
1960	8.10779947470595
1961	8.394160583941606
1962	7.901936026936027
1963	7.182738714867039
1964	7.6233616037008485
1965	8.05084745762712
1966	7.881580237231643
1967	8.547677261613693
1968	8.807551874610384
1969	8.755445459981209
1970	9.456323553787502
1971	10.032225237449117
1972	9.881948244859668
1973	9.73537813862577
1974	9.597310307939177
1975	11.627705627705627
1976	11.453567702062765
1977	12.134230363945854
1978	11.941574081267966
1979	12.308157556513192
1980	12.629482071713147
1981	13.422585412501087
1982	14.393521074912572
1983	16.006006006006004
1984	15.73055773762765
1985	16.265477959385834
1986	17.69063611220861
1987	18.213228035538005
1988	19.361103019710654
1989	19.541882307839757
1990	19.143529411764707
1991	18.580959249909846
1992	19.662818398387394
1993	20.70381779146831
1994	20.43769539973202
1995	20.451491534533726
1996	20.05821419399024
1997	20.751231527093594
1998	20.794975479652415
1999	21.668443496801707
2000	21.491882404563402
2001	22.01290772719344
2002	23.46046511627907
2003	23.14608742099172
2004	24.19412929947776
2005	24.105145413870247
2006	24.28694900605013
2007	25.195508321636257
2008	26.22397841171935
2009	27.494043302600225
2010	25.182724252491695
2011	28.412732322153385
2012	26.65796912372255
2013	26.059957173447536
2014	28.628663003663007