Year	% of total
1990	3.6112909835380527
1991	4.110258102751191
1992	4.10976075054312
1993	4.1307598501944875
1994	4.159390217265218
1995	3.863818080451394
1996	4.337578379993094
1997	4.349011265172279
1998	4.230578426787133
1999	4.270369152591534
2000	4.326882410599765
2001	4.195546315352451
2002	4.169615016671716
2003	4.147840790519982
2004	4.139023430735186
2005	4.353320107096005
2006	4.530296359877998
2007	4.541934204392602
2008	4.820601992529142