Year	% of total
1990	24.804079213924805
1991	24.813367044946308
1992	24.880299862829705
1993	24.94094345440642
1994	24.760488438545924
1995	24.992834099314443
1996	25.21774224913542
1997	26.38112502865979
1998	26.54525487230538
1999	26.221258640153163
2000	26.695091690656415
2001	27.586423725484252
2002	28.63150747975395
2003	30.507725154404014
2004	31.124613698518917
2005	32.51208246652411
2006	33.74171238544063
2007	35.44712668194299
2008	36.84398971132154