Year	Percent
1990	35.1
1992	35.5
1993	36
1994	31
1995	31.3
1996	31.8
1997	29.7
1998	34.3
1999	32.8
2000	32.8
2002	33.5
2003	35.76
2004	36.31
2005	36.98
2006	33.47
2007	34.96
2008	35.28