Year	% of total fuel combustion
1971	5.889724310776942
1972	5.3885853066180935
1973	6.333038086802481
1974	6.905073411833115
1975	6.505728314238953
1976	5.368852459016393
1977	5.463401790416009
1978	4.504618499304062
1979	4.959883296863603
1980	5.490887713109935
1981	5.5507586036758365
1982	5.524661508704062
1983	5.498154981549815
1984	5.264483627204029
1985	5.277879119542746
1986	5.685779540810194
1987	5.637982195845697
1988	5.638374609281077
1989	5.376604504722693
1990	4.11693710607483
1991	5.546723193782017
1992	7.484753280354832
1993	8.62227114290956
1994	6.719139950086389
1995	5.517633674630261
1996	6.468597216998871
1997	4.093567251461989
1998	4.52876376988984
1999	4.20539033457249
2000	3.1998103816070165
2001	2.77592715967133
2002	3.789126853377265
2003	3.8091161994436122
2004	2.925764192139738
2005	2.731182795698925
2006	3.189926547743967
2007	2.6083545793292804
2008	2.7817844632186275
2009	2.6415094339622645
2010	2.9054054054054057
2011	3.007518796992481
2012	3.2170978627671545
2013	3.0757498729028976
2014	2.2549252314265367