Year	Percent
1990	61.63
1991	61.71
1992	61.99
1993	62.29
1994	62.5
1995	62.68
1996	62.96
1997	62.99
1998	62.9
1999	62.69
2000	62.38
2001	62.04
2002	61.69
2003	61.24
2004	60.87
2005	60.6
2006	60.5
2007	60.52
2008	60.84
2009	61.1
2010	61.25
2011	61.4
2012	61.42
2013	61.27
2014	61.07
2015	60.86
2016	60.67
2017	60.52
2018	60.4
2019	60.26