Year	% of total fuel combustion
1971	3.8426051560379912
1972	3.7666753858226536
1973	3.5838701980434267
1974	3.615965880116822
1975	3.3708351363046285
1976	3.2551343453202377
1977	3.396395661746718
1978	3.701880035810206
1979	3.013373218370579
1980	2.9966147030551262
1981	2.732305731469311
1982	2.388703507772443
1983	2.90778061758914
1984	2.6042288854378213
1985	2.600795445683538
1986	2.4843260188087775
1987	2.588724989046298
1988	2.6292821296094266
1989	2.4870094965060026
1990	2.2887567418061123
1991	2.4641089543332515
1992	2.396506426187602
1993	3.076173574137871
1994	3.165875482394727
1995	3.3420707732634343
1996	3.1802456596946733
1997	2.8138724822050594
1998	2.618512826575245
1999	2.7883162147990497
2000	2.3556484088775846
2001	2.01216531798186
2002	1.9336143308746054
2003	1.8413633074677511
2004	1.6393442622950825
2005	1.5644947888860523
2006	1.8786951857009153
2007	1.9910587722167705
2008	1.8308631211857018
2009	1.9167440682259558
2010	2.0443035368715776
2011	2.6645278223370354
2012	2.8588074574091937
2013	2.802410841107144
2014	2.7105875401602724