Year	% of total fuel combustion
1990	6.078233012982634
1991	7.343210878830932
1992	6.272039304251358
1993	6.099704032556418
1994	4.654392100390867
1995	5.371803893971381
1996	5.537569135302848
1997	5.604203152364273
1998	6.182753781381569
1999	5.021570319240725
2000	8.375
2001	7.506407909190773
2002	7.635694572217113
2003	6.417390014096001
2004	6.304214193019603
2005	6.087067372044109
2006	6.089169027930376
2007	6.464020513916341
2008	5.985059068797776
2009	6.137148495313271
2010	5.947804061694333
2011	5.732294195306844
2012	6.235299148954368
2013	5.508746589632483
2014	6.106665474540659