Year	% of total fuel combustion
1971	10.267857142857142
1972	10.931174089068826
1973	9.537572254335261
1974	13
1975	9.127789046653145
1976	18.39080459770115
1977	19.506172839506174
1978	21.932114882506525
1979	14.975845410628018
1980	15.04297994269341
1981	14.033018867924527
1982	14.87513572204126
1983	14.435146443514643
1984	11.924882629107982
1985	11.704119850187267
1986	10.886742756804214
1987	10.834049871023216
1988	11.378737541528242
1989	12.39282930631333
1990	11.826226870474658
1991	10.852148579752367
1992	10.934256055363322
1993	10.936476751800917
1994	11.090342679127724
1995	11.705288175876412
1996	11.91151446398185
1997	12.258737610850286
1998	12.095984329089129
1999	10.15521064301552
2000	11.388235294117646
2001	11.659991099243436
2002	10.922787193973633
2003	12.064631956912027
2004	12.184057031756318
2005	14.24698795180723
2006	14.694408322496749
2007	13.353390418884517
2008	17.346500644053243
2009	21.363275039745627
2010	18.388791593695274
2011	16.121830649019294
2012	15.005646527385657
2013	16.12858909190823
2014	18.245071511403168