Year	Percent
1993	44.14
1994	42.19
1995	43.08
1996	41.91
1997	40.38
1998	39.34
1999	37.68
2000	37.41
2001	38.2
2002	38.5
2003	36.87
2004	35.96
2005	36.89
2006	35.33
2007	34.85
2008	34.96
2009	32.98
2010	32.45
2011	31.5
2012	30.81
2013	30.88
2014	30.75
2015	31.62
2016	32.91
2017	33.05