Year	Percent
1990	60.01
1991	60.33
1992	60.5
1993	60.46
1994	61.22
1995	61.65
1996	62.03
1997	62.54
1998	60.71
1999	60.65
2000	61.15
2001	61.31
2002	61.89
2003	61.44
2004	62.23
2005	62.14
2006	62.04
2007	61.96
2008	61.43
2009	60.67
2010	60.79
2011	60.98
2012	61.24
2013	61.36
2014	62.38
2015	62.7
2016	62.8
2017	63.13
2018	63.02
2019	63.26
2020	62.6