Year	% of total fuel combustion
1990	2.916120576671035
1991	3.7820252135014236
1992	9.02217741935484
1993	14.647058823529413
1994	16.437364228819696
1995	19.680403700588727
1996	14.201762977473068
1997	15.35982814178303
1998	15.183867141162516
1999	17.366946778711483
2000	15.443425076452598
2001	15.497076023391815
2002	16.379310344827587
2003	17.952127659574472
2004	21.762349799732974
2005	19.74025974025974
2006	20.63914780292943
2007	17.639077340569877
2008	14.597544338335608
2009	15.818431911966988
2010	15.668789808917197
2011	15.256410256410255
2012	15.858453473132371
2013	17.91044776119403
2014	15.17241379310345