Year	% of total fuel combustion
1990	42.40918969264204
1991	42.88214702450408
1992	44.9531737773153
1993	47.6252439817827
1994	50.381150381150384
1995	47.72896500372301
1996	51.04241552839683
1997	49.00369003690037
1998	52.414275717284816
1999	50.7563025210084
2000	49.510763209393346
2001	50.78196872125115
2002	48.673376029277215
2003	47.84995425434583
2004	46.626297577854665
2005	46.45476772616137
2006	42.25806451612903
2007	37.90901835594573
2008	39.40609951845907
2009	43.439716312056746
2010	44.46267432321575
2011	39.91189427312776
2012	39.52464788732395
2013	36.34669151910531
2014	30.940834141610086