Year	Percent
1994	39.65
1995	38.88
1996	39.54
1997	39.29
1998	39.44
1999	38.43
2000	37.24
2001	37.05
2002	38.15
2003	38.09
2004	39.12
2005	38.75
2006	38.79
2007	39.37
2008	40.12
2009	37.92
2010	37.11
2011	37.48
2012	37.53
2013	35.82
2014	35.44
2015	36.1
2016	36.46
2017	37.16