Year	% of total fuel combustion
1990	79.4010889292196
1991	77.67944936086529
1992	72.49666221628837
1993	68.52589641434264
1994	68.70748299319727
1995	69.51219512195121
1996	67.1171171171171
1997	66.39999999999999
1998	70.28985507246377
1999	69.9604743083004
2000	71.55963302752293
2001	69.33962264150942
2002	72.11538461538461
2003	71.29186602870814
2004	71.2
2005	69.36170212765957
2006	70.19607843137256
2007	81.9935691318328
2008	84.7457627118644
2009	86.14718614718615
2010	86.95652173913044
2011	86.77685950413225
2012	63.02816901408451
2013	69.971671388102
2014	60.515021459227455