Year	Percent
1993	36.7
1995	39.3
1996	39.7
2004	43.5
2005	45.4
2006	42.6
2007	44
2008	43.5
2009	42.6
2010	41.7
2011	42.8
2012	42.3
2013	42.6
2014	42.2
2015	41.5