Year	% of total fuel combustion
1990	18.953488372093023
1991	16.8057210965435
1992	16.30695443645084
1993	12.94797687861272
1994	10.645933014354068
1995	10.456730769230768
1996	11.752786220871329
1997	10.454545454545453
1998	12.836438923395447
1999	10.011248593925758
2000	12.309495896834703
2001	10.368663594470046
2002	10.565110565110563
2003	12.669683257918555
2004	10.760233918128655
2005	12.696629213483144
2006	14.157303370786517
2007	15.631691648822269
2008	14.238773274917852
2009	9.624413145539906
2010	14.98800959232614
2011	15.829694323144103
2012	15.664018161180474
2013	16.13722998729352
2014	15.074024226110366