Year	% of total fuel combustion
1992	4.545454545454546
1993	6.349206349206349
1994	7.042253521126761
1995	7.692307692307692
1996	5.882352941176471
1997	6.25
1998	6.779661016949152
1999	6.349206349206349
2000	6.557377049180328
2001	5.970149253731343
2002	6.0606060606060606
2003	5.970149253731343
2004	6.0606060606060606
2005	5.172413793103448
2006	4
2007	4.081632653061225
2008	4.651162790697675
2009	4.444444444444445
2010	4.166666666666667
2011	3.9215686274509802
2012	3.6363636363636362
2013	3.6363636363636362
2014	3.571428571428571