Year	Percent
1990	12.93
1991	12.86
1992	12.79
1993	12.71
1994	12.64
1995	12.57
1996	12.49
1997	12.42
1998	12.35
1999	12.27
2000	12.2
2001	12.12
2002	12.05
2003	11.98
2004	11.9
2005	11.83
2006	11.76
2007	11.68
2008	11.61
2009	11.54
2010	11.46