Year	% of total fuel combustion
1990	44.75
1991	40.61481136469493
1992	43.314500941619585
1993	44.80179506357517
1994	22.149837133550488
1995	24.085365853658537
1996	50.847457627118644
1997	69.35866983372921
1998	74.4600938967136
1999	75.02401536983669
2000	65.08746355685132
2001	65.03703703703704
2002	67.29957805907173
2003	71.34020618556701
2004	67.74193548387098
2005	66.77175283732663
2006	68.28849456210648
2007	67.75244299674267
2008	67.04545454545455
2009	69.56952003958436
2010	67.74036115178137
2011	70.85470085470087
2012	70.02309468822172
2013	70.9902370990237
2014	70.72155411655874