Year	% of total fuel combustion
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0.4050222762251924
1984	0.3450439146800502
1985	0.39303761931499165
1986	0.3748125937031484
1987	0.3618272274988693
1988	0.704070407040704
1989	0.5964979796036175
1990	0.578368999421631
1991	0.4902789518174133
1992	0.4774535809018568
1993	0.4363148179224702
1994	0.4422754308372732
1995	0.4164273406088455
1996	0.34383166001925464
1997	0.33920417482061316
1998	0.33159035837265655
1999	0.3349460364719018
2000	0.400851810096455
2001	0.507998270644185
2002	0.12693039983075946
2003	0.12149438088488408
2004	0.12382131631583962
2005	0.11700117001170011
2006	0.11302382194400974
2007	0.1369311316955296
2008	0.20480611687602404
2009	0.3333333333333333
2010	0.3624382207578254
2011	0.421012944577102
2012	0.32371983519717484
2013	0.501527641667147
2014	0.5244256968591461