Year	% of total fuel combustion
1990	22.07287933094385
1991	26.666666666666668
1992	20.342396777442097
1993	19.599248591108324
1994	20.57692307692308
1995	11.193111931119311
1996	19.115323854660346
1997	17.153284671532845
1998	15.682281059063136
1999	14.840182648401829
2000	14.038876889848813
2001	9.763313609467456
2002	9.574468085106384
2003	11.589403973509933
2004	8.125
2005	7.389162561576355
2006	9.513274336283187
2007	8.990825688073393
2008	13.49036402569593
2009	12.098298676748582
2010	11.62324649298597
2011	17.310924369747898
2012	16.338880484114977
2013	25.411061285500747
2014	20.984455958549226