Year	% of total fuel combustion
1971	15.6282373834542
1972	14.674763960715474
1973	14.669869077893948
1974	13.182773109243698
1975	13.097185863874344
1976	13.177216168173738
1977	13.38999055712937
1978	14.319845857418112
1979	14.402839396628215
1980	13.3108904224878
1981	13.537467302661948
1982	12.83281155757245
1983	12.92316829544841
1984	13.454581495614253
1985	12.38827441454614
1986	11.238681166327282
1987	10.814528347021769
1988	11.25780351181607
1989	10.924472995980553
1990	11.31235992363244
1991	10.96313063970976
1992	10.265648764784926
1993	9.964247508586226
1994	10.204898351208582
1995	9.940907240405139
1996	9.755868102921117
1997	10.100717177688301
1998	9.695467111325636
1999	9.548718677947852
2000	9.053244005641748
2001	8.83446546439792
2002	8.890087710323403
2003	8.9654795817141
2004	8.566785392511012
2005	8.325433423847551
2006	7.9879381831888425
2007	7.48301189339233
2008	7.214686317986174
2009	6.855131538876004
2010	6.833185453043824
2011	6.85220964333807
2012	6.455783399556737
2013	6.379610804530933
2014	6.138159890100088