Year	% of total fuel combustion
1971	3.669724770642202
1972	3.7500000000000013
1973	3.952569169960476
1974	3.6496350364963495
1975	3.726708074534163
1976	3.1161473087818696
1977	3.2
1978	2.702702702702702
1979	2.2113022113022107
1980	2.1377672209026146
1981	3.3112582781456954
1982	2.464065708418891
1983	4.251012145748989
1984	4.3572984749455355
1985	4.1763341067285396
1986	2.1686746987951797
1987	1.8390804597701143
1988	2.1126760563380302
1989	1.906779661016951
1990	1.3592233009708747
1991	2.1276595744680846
1992	2.0332717190388165
1993	0.7104795737122565
1994	0.6557377049180315
1995	0.7256894049346887
1996	0.3091190108191642
1997	0.30816640986132393
1998	0.28818443804034616
1999	0.45871559633027575
2000	8.591549295774646
2001	8.81057268722467
2002	8.811188811188812
2003	8.823529411764703
2004	11.384976525821594
2005	9.92282249173098
2006	11.246200607902738
2007	10.287303058387396
2008	11.243611584327086
2009	9.999999999999998
2010	12.91970802919708
2011	12.84465366509751
2012	17.7525403466826
2013	13.778829095209932
2014	14.863387978142079