Year	% of total fuel combustion
1971	4.195000478881335
1972	4.085836909871244
1973	4.203900846996659
1974	4.182220378819302
1975	4.263897373243738
1976	4.252591088791537
1977	4.404233526800956
1978	4.3089882440062945
1979	4.1796045105409405
1980	4.275391409072662
1981	4.708605251176201
1982	5.18910014414167
1983	5.458095524181437
1984	5.671322369903132
1985	4.870701146360969
1986	4.916351010101009
1987	4.433583522429744
1988	4.36505078153137
1989	3.773287732877329
1990	4.444347522679693
1991	4.7215849843587065
1992	4.549797447068717
1993	3.7049038669259025
1994	3.261051154398743
1995	3.3369634120572793
1996	3.1055509162241806
1997	2.8203764441686627
1998	3.1459271886034346
1999	3.2129338927848363
2000	3.118011719081722
2001	3.6749867233138604
2002	2.701134605466737
2003	2.5639737195834327
2004	2.7570956396955895
2005	3.1891280221095455
2006	3.4253419096983717
2007	3.5612393511960576
2008	2.809841166189717
2009	2.8149680158868153
2010	2.6914945519596674
2011	2.5694382423863527
2012	2.421765651189715
2013	2.437886090557329
2014	2.277049220814504