Year	Percent
1996	27.22
1997	25.75
1998	27.05
1999	25.76
2000	26.76
2001	26.25
2002	25.53
2003	27.07
2004	26.94
2005	26.48
2006	27.35
2007	28.6
2008	29.39
2009	24.34
2010	23.07
2011	22.9
2012	23.47
2013	23.9
2014	23.84
2015	23.64
2016	24.1
2017	23.29