Year	% of total energy
1990	0.44760278683061516
1991	0.496903985586448
1992	0.6404267514707862
1993	0.8047338961084761
1994	1.2820562662577024
1995	1.5784480974404775
1996	1.9940006423306103
1997	2.199441197399429
1998	2.420257204698311
1999	2.628255595390769
2000	3.032325826806016
2001	3.364239726347964
2002	3.4021938355657184
2003	3.2725638942741186
2004	3.2158220646997338
2005	3.6154062261657
2006	3.741237992952097
2007	3.842221839637662
2008	3.8441228267737495
2009	4.082470003973583
2010	4.327536960600212
2011	4.25518056214298
2012	4.145977778510045
2013	4.464702397755711
2014	4.014009181117033