Year	Percent
1996	29.11
1997	29.54
2001	26.42
2002	29.82
2003	30.23
2004	29.63
2005	28.62
2006	29.32
2007	30.63
2008	30.84
2009	29.01
2010	27.43
2011	27.92
2012	27.87
2013	27.59
2014	26.93
2015	26.67
2016	26.92
2017	26.38