Year	% of total fuel combustion
1971	6.656671664167917
1972	5.570060922541337
1973	5.9989567031820545
1974	5.285678328718853
1975	5.505226480836238
1976	5.191727703576046
1977	5.14456630109671
1978	4.830216088614491
1979	4.899738448125546
1980	4.799627213420316
1981	3.823953823953824
1982	3.7389351301360807
1983	3.0024274945700773
1984	2.538840469874952
1985	3.056106380496909
1986	2.4229325446479355
1987	3.08561056771201
1988	2.850014394012091
1989	2.713284166439042
1990	28.91270372851083
1991	28.17949808592088
1992	24.524541151067186
1993	25.511041786388642
1994	26.56504239102509
1995	5.218146299110049
1996	3.876261040646324
1997	3.4558021098581304
1998	4.281894576012223
1999	3.2703990687183953
2000	3.52852312783253
2001	3.141507783802694
2002	2.8810663021189336
2003	2.516934291510505
2004	2.494602225543928
2005	2.412113581392267
2006	2.863528878235237
2007	3.0420041439065724
2008	2.6851587980114617
2009	2.4631356212391706
2010	3.367468139064557
2011	2.9636391297733145
2012	3.5279696235835796
2013	3.7189701313482417
2014	3.469406420535958