Year	% of total fuel combustion
1971	4.195000478881335
1972	4.085836909871244
1973	4.203900846996659
1974	4.182220378819301
1975	4.263897373243739
1976	4.252591088791537
1977	4.404233526800955
1978	4.308988244006295
1979	4.17960451054094
1980	4.275391409072661
1981	4.708605251176201
1982	5.18910014414167
1983	5.458095524181438
1984	5.671322369903132
1985	4.87070114636097
1986	4.9163510101010095
1987	4.433583522429744
1988	4.365050781531371
1989	3.773287732877328
1990	4.444347522679694
1991	4.7215849843587065
1992	4.549797447068717
1993	3.7049038669259025
1994	3.261051154398742
1995	3.3369634120572793
1996	3.1055509162241806
1997	2.8203764441686627
1998	3.145927188603435
1999	3.2129338927848363
2000	3.1180117190817205
2001	3.67498672331386
2002	2.701134605466736
2003	2.563973719583433
2004	2.7570956396955895
2005	3.189128022109546
2006	3.4253419096983713
2007	3.5612393511960576
2008	2.8098411661897167
2009	2.8149680158868153
2010	2.6914945519596674
2011	2.569438242386353
2012	2.421765651189715
2013	2.437886090557329
2014	2.2770492208145034