Year	% of total fuel combustion
1990	13.532232285562069
1991	16.91860465116279
1992	15.184381778741866
1993	17.120954003407153
1994	16.074950690335303
1995	11.573033707865168
1996	11.348314606741573
1997	10.451306413301662
1998	9.838107098381073
1999	10.256410256410255
2000	9.649122807017543
2001	10.896551724137932
2002	11.065006915629322
2003	11.126005361930295
2004	11.898395721925132
2005	11.609498680738787
2006	11.581569115815691
2007	11.124401913875598
2008	11.335012594458437
2009	12.534818941504177
2010	12.608158220024723
2011	12.534059945504087
2012	12.303290414878399
2013	11.866859623733719
2014	12.648809523809526