Year	% of total fuel combustion
1971	22.94843863471315
1972	21.829521829521827
1973	21.980830670926515
1974	21.997471554993677
1975	21.75502742230347
1976	21.783980582524272
1977	20.943613348676642
1978	21.743810548977397
1979	21.684210526315788
1980	21.96286472148541
1981	20.824847250509162
1982	21.26134734830387
1983	21.62534435261708
1984	19.982355535950592
1985	20.361990950226247
1986	19.797904191616766
1987	19.76543635736461
1988	19.387422613229063
1989	19.02973395931142
1990	24.474245656811945
1991	24.90996398559424
1992	25.513361462728557
1993	24.436475409836063
1994	24.516129032258064
1995	25.094718074437267
1996	25.270988310308184
1997	25.710804224207962
1998	23.909957412289593
1999	24.71400394477317
2000	24.366222870691225
2001	23.64575908766928
2002	23.30801687763713
2003	23.430070503361204
2004	23.148602256007848
2005	22.895050178601807
2006	22.209677419354836
2007	22.5645813881108
2008	24.786722506592216
2009	24.592731829573932
2010	24.0245506356861
2011	23.200000000000003
2012	23.257390832655275
2013	23.38161395211351
2014	26.093677539032306