Year	Percent
1990	59.65
1991	59.94
1992	60.33
1993	60.59
1994	60.89
1995	61.16
1996	60.47
1997	59.74
1998	59
1999	59.81
2000	60.4
2001	60.21
2002	59.84
2003	59.09
2004	58.54
2005	57.97
2006	57.37
2007	55.91
2008	56.36
2009	55.27
2010	55.32
2011	55.4
2012	55.57
2013	55.83
2014	56.12
2015	56.38
2016	56.58
2017	56.72
2018	56.83
2019	56.93