Year	% of total fuel combustion
1990	30.74596774193548
1991	37.71760154738878
1992	45.63380281690141
1993	16.463414634146343
1994	30.597014925373127
1995	41.246290801186944
1996	64.16666666666667
1997	56.9620253164557
1998	54.57317073170732
1999	49.829351535836174
2000	46.78362573099415
2001	44.50867052023121
2002	31.615120274914087
2003	26.911314984709477
2004	22.254335260115607
2005	23.00242130750605
2006	21.686746987951803
2007	22.500000000000004
2008	19.734345351043643
2009	15.222482435597193
2010	15.555555555555555
2011	20.342612419700213
2012	26.286764705882348
2013	25.190839694656486
2014	29.693486590038315