Year	Percent
1995	18.6
1996	18.62
1997	18.61
1998	17.74
1999	17.37
2000	17.45
2001	16.38
2002	16.47
2003	16.24
2004	16.39
2005	16.45
2006	16.17
2007	15.85
2008	15.71
2009	15.9
2010	16.1