Year	Percent
1993	45.09
1994	45.83
1995	46.37
1996	47.74
1997	47.22
1998	48.2
1999	51.19
2000	52.41
2001	50.86
2002	51.25
2003	54.07
2004	53.3
2005	53.58
2006	54.68
2007	54.27
2008	56.04
2009	57.41
2010	58.37
2011	59.45
2012	60.32
2013	60.17
2014	59.09
2015	60.17
2016	61.31
2017	60.83