Year	Percent
1993	39.99
1994	38.56
1995	35.93
1996	36.01
1997	34.35
1998	34.44
1999	34.98
2000	37.22
2001	37.99
2002	40.73
2003	41.38
2004	43.69
2005	43.3
2006	43.9
2007	44.73
2008	44.18
2009	45.04
2010	50.24
2011	49.63
2012	46.81
2013	49.76
2014	51.3
2015	51.26
2016	50.65
2017	52