Year	% of total fuel combustion
1971	20.98039215686275
1972	26.750448833034106
1973	22.413793103448278
1974	23.06163021868787
1975	27.3921200750469
1976	26.007326007326004
1977	25.278810408921938
1978	26.923076923076923
1979	28.739495798319325
1980	22.846441947565545
1981	19.832985386221296
1982	23.76681614349776
1983	9.497206703910615
1984	8.41121495327103
1985	8.970099667774088
1986	7.094594594594595
1987	12.650602409638553
1988	30.444964871194387
1989	34.41558441558442
1990	14.444444444444446
1991	21.791767554479417
1992	24.168514412416854
1993	14.858490566037736
1994	3.307888040712468
1995	12.756264236902052
1996	18.128654970760234
1997	13.294797687861271
1998	11.214953271028037
1999	25.3125
2000	13.948919449901767
2001	6.828193832599119
2002	6.265060240963854
2003	6.87960687960688
2004	24.23076923076923
2005	22.524271844660195
2006	33.223684210526315
2007	22.44165170556553
2008	40.82998661311914
2009	38.92617449664429
2010	20.13422818791946
2011	31.71745152354571
2012	39.60880195599022
2013	25.879043600562586
2014	15.47049441786284