Year	% of total fuel combustion
1990	4.114539894356408
1991	4.48499845344881
1992	2.9523407844791225
1993	3.0269675288937803
1994	3.2898468519568915
1995	3.3834586466165413
1996	3.959810874704492
1997	3.878787878787879
1998	3.517587939698493
1999	3.221476510067114
2000	3.445899379738112
2001	3.6072144288577155
2002	3.1571722717913517
2003	3.0797101449275366
2004	3.128760529482551
2005	3.032104637336504
2006	2.8332260141661303
2007	2.016546018614271
2008	2.1959459459459456
2009	2.371273712737127
2010	1.93029490616622
2011	2.258610954263128
2012	2.6155717761557176
2013	2.2269353128313893
2014	2.5114155251141557