Year	Percent
1990	60.46
1991	60.89
1992	61.32
1993	61.78
1994	62.24
1995	62.71
1996	63.18
1997	63.17
1998	63.17
1999	63.17
2000	63.17
2001	63.16
2002	63.16
2003	63.15
2004	63.13
2005	63.11
2006	63.05
2007	62.97
2008	62.88
2009	62.77
2010	62.67
2011	62.63
2012	62.62
2013	62.75
2014	62.93
2015	63.07
2016	63.2
2017	63.34
2018	63.59
2019	63.85