Year	% of total
1990	26.51413189771198
1991	26.498637602179837
1992	28.224023581429623
1993	27.81456953642384
1994	27.711738484398218
1995	26.517341040462426
1996	26.118326118326117
1997	25.813449023861175
1998	25.471698113207548
1999	25.283875851627556
2000	25.68881685575365
2001	25.31328320802005
2002	24.701873935264054
2003	23.875432525951556
2004	22.96231375985977
2005	22.970479704797047
2006	22.94489611562782
2007	24.47368421052632
2008	26.297577854671278