Year	Percent
2000	23.7
2001	24.8
2002	24.9
2003	33.9
2004	44.4
2005	42.8
2006	38.8
2007	39.1
2008	38.8
2009	37.9
2010	37.3
2011	36.5
2012	36.8
2013	36.3