Year	Percent
1990	76.1
1991	75.5
1992	74.6
1993	76
1994	77.4
1995	78.8
1996	78.9
1997	78.9
1998	63.7
1999	63.8
2000	68.4
2001	65.4
2004	65.8
2008	75.18
2009	75.18