Year	% of total fuel combustion
1971	23.860329776915616
1972	24.107919930374237
1973	24.915254237288135
1974	26.67706708268331
1975	28.01030264005151
1976	28.526970954356845
1977	31.5319781854239
1978	31.924262439453983
1979	32.27752639517345
1980	37.43804803659931
1981	44.23762376237624
1982	49.521354933726066
1983	44.10452517527087
1984	44.108940201302545
1985	42.17597471022129
1986	38.28032979976443
1987	39.227272727272734
1988	36.92962887852362
1989	38.20720058780309
1990	41.534644016033596
1991	42.31035277841827
1992	35.05045940653713
1993	27.891621129326044
1994	25.091093117408906
1995	25.98276224511246
1996	24.779396675559205
1997	20.8074262194588
1998	30.575903005809547
1999	39.760223353588444
2000	37.40068104426788
2001	35.908298031397955
2002	36.95912661429903
2003	30.99036941210292
2004	33.1183090859182
2005	35.59808612440191
2006	37.51450116009281
2007	41.4306289006241
2008	34.13926499032882
2009	27.629718263896443
2010	27.011882909863782
2011	29.75460122699386
2012	28.241070721469864
2013	26.18184508396834
2014	20.58427284974828