Year	Percent
1990	57
1991	58
1992	58
1993	58
1994	58
1995	60.4
1996	60.8
1997	61.3
1998	61.3
1999	61.9
2000	62.8
2001	63
2002	64
2003	64.33
2004	64.5
2005	64.89
2006	64.96
2007	65.41
2008	65.89
2009	66.2