Year	Percent
1990	61.82
1991	61.83
1992	61.86
1993	61.9
1994	61.88
1995	61.79
1996	61.31
1997	60.89
1998	60.62
1999	60.58
2000	60.74
2001	60.59
2002	60.64
2003	60.92
2004	61.38
2005	61.92
2006	61.86
2007	61.96
2008	62.26
2009	62.72
2010	63.22
2011	63.06
2012	62.98
2013	63.08
2014	63.36
2015	63.72
2016	63.33
2017	63.06
2018	63.02
2019	63.19