Year	% of total fuel combustion
1960	6.683217197506134
1961	6.404195406752951
1962	6.22251701181615
1963	5.816030363920519
1964	5.228308190746177
1965	5.380244923029674
1966	4.762395806479332
1967	3.9902573971614137
1968	3.430548415333954
1969	3.002962231547766
1970	9.04980973476458
1971	14.632735389277961
1972	14.602333544827989
1973	14.306878495192924
1974	14.262262701635027
1975	14.806082266123958
1976	14.671816205949787
1977	14.805882009004268
1978	14.653653061014962
1979	14.501177431836823
1980	14.051217139259856
1981	14.741464076221478
1982	15.00223451017536
1983	15.167911050777336
1984	15.133090856450067
1985	15.795492888773428
1986	15.67229038116715
1987	15.368225494357679
1988	15.297293980487211
1989	14.64730402838409
1990	14.259387940991427
1991	13.59696262998389
1992	12.76540133648141
1993	12.471009129040215
1994	11.328291267952014
1995	11.227192519692203
1996	10.20922408103532
1997	10.703745783399517
1998	9.519366354072202
1999	10.003110387477824
2000	9.247249613582076
2001	8.978875488668013
2002	8.712595812280071
2003	8.200694534902736
2004	7.970761179125365
2005	7.530951289603391
2006	7.0582233165650985
2007	6.692401241552062
2008	6.329349235079121
2009	6.244954451415646
2010	5.950739109362527
2011	5.737989222703685
2012	5.718826081254883
2013	5.752742788285353
2014	5.6974471985490585