Year	Percent
1999	44.2
2001	43.9
2002	43.5
2003	42.2
2004	45.8
2005	44.7
2006	38.8
2007	40
2008	38.4
2009	37.5
2010	39.4
2011	38.6
2012	38.7
2013	39.4
2014	40.1
2015	40.7
2016	40.2