Year	Percent
1995	15.61
1996	15.8
1997	15.9
1998	15.76
1999	15.79
2000	15.95
2001	16.74
2002	16.71
2003	17.01
2004	17.63
2005	17.58
2006	17.78
2007	18.09
2008	18.4
2009	18.4
2010	18.4