Year	% of total fuel combustion
1992	63.63636363636365
1993	52.380952380952394
1994	45.07042253521128
1995	39.743589743589745
1996	38.82352941176471
1997	38.75000000000001
1998	40.67796610169492
1999	46.03174603174603
2000	45.9016393442623
2001	43.28358208955224
2002	39.39393939393939
2003	40.298507462686565
2004	43.939393939393945
2005	48.27586206896552
2006	52
2007	55.102040816326536
2008	53.48837209302326
2009	55.55555555555556
2010	54.16666666666667
2011	56.86274509803923
2012	56.36363636363636
2013	56.36363636363636
2014	55.35714285714285