Year	Percent
1993	4.6
1996	4.3
2004	3.6
2005	3.8
2006	3.7
2007	3.9
2008	3.9
2009	3.8
2010	3.7
2011	3.7
2012	3.9
2013	3.8
2014	3.9
2015	3.9