Year	% of total fuel combustion
1990	7.212003872216845
1991	6.102927109240482
1992	4.702455264253016
1993	6.311360448807854
1994	6.724845995893223
1995	6.118332586284178
1996	8.874709976798144
1997	11.189927292073062
1998	8.704920945105703
1999	6.4636885450461685
2000	5.4186046511627906
2001	8.21127385707945
2002	9.229188078108942
2003	9.423482091553343
2004	11.130804679191776
2005	13.239152371342078
2006	13.703131039814457
2007	11.046859421734796
2008	14.111318021932547
2009	14.013575651412305
2010	14.080209241499563
2011	11.608391608391608
2012	11.47210396594219
2013	12.433978873239438
2014	15.481500918394122