Year	Percent
1990	31.4
1991	32
1992	32.6
1993	33.3
1994	33.9
1995	34.6
1997	34.7
1998	34.7
1999	34.7
2000	34.7
2004	79.1
2005	78.41
2006	78.03
2007	80.06
2008	81.12