Year	% of total
1990	3.6079324801622197
1991	4.065544758148286
1992	4.07379385483158
1993	4.106156324870964
1994	4.1082570604810575
1995	3.84923648194878
1996	4.286936858667205
1997	4.315197735570757
1998	4.224172434373096
1999	4.274785659070474
2000	4.323880357839153
2001	4.196561325576293
2002	4.170017539036713
2003	4.1378524819151306
2004	4.125827219072105
2005	4.312762418171627
2006	4.467938112996325
2007	4.496848814512546
2008	4.753594944535441