Year	% of total fuel combustion
1990	51.87977570527907
1991	49.01795304587999
1992	48.23776866515836
1993	52.78741755454085
1994	53.680518341696306
1995	51.58070304010513
1996	47.98010644795392
1997	47.032636394338525
1998	48.03355200887757
1999	47.822357133430124
2000	47.51186440677966
2001	45.482615116122965
2002	44.950166112956815
2003	46.402964391155024
2004	41.80389343594092
2005	47.07583438233593
2006	45.778057840275935
2007	45.15929979539476
2008	46.40252383052342
2009	48.39640795381655
2010	48.77004544259587
2011	49.29506906176197
2012	51.20695321915058
2013	51.011244434382306
2014	49.97463431132155