Year	Percent
1993	31.3
2003	28.4
2004	25.9
2005	26.1
2006	26.8
2007	24
2008	24.9
2009	24.4
2010	24.3
2011	24.7
2012	25.2
2013	26.6
2014	26.2
2015	24.4