Year	Percent
1990	12.8
1991	13.3
1992	13.8
1993	14.3
1994	13.6
1995	13.8
1996	12.1
1997	12.1
1998	12.1
1999	12.1
2000	12.1
2004	14.12
2008	14.59
2009	14.33