Year	Percent
1990	59.26
1991	59.04
1992	59.18
1993	59.32
1994	59.74
1995	60.18
1996	59.91
1997	59.3
1998	58.9
1999	58.77
2000	59.09
2001	59.39
2002	59.71
2003	60.06
2004	60.43
2005	60.86
2006	61.22
2007	61.65
2008	62.12
2009	62.59
2010	63.02
2011	63.36
2012	63.67
2013	63.93
2014	64.12
2015	64.26
2016	64.37
2017	64.43
2018	64.53
2019	64.06
2020	63.12