Year	Percent
1995	15.01
1996	17.41
1997	17.17
1998	17.13
1999	17.15
2000	18.33
2001	17.5
2002	17.68
2003	17.68
2004	17.4
2005	17.66
2006	17.92
2007	18.39
2008	18.58
2009	18.73
2010	18.73