Year	Percent
1990	63.48
1991	63.7
1992	62.74
1993	62.15
1994	61.89
1995	61.95
1996	61.6
1997	61.33
1998	61.3
1999	61.27
2000	61.27
2001	61.25
2002	61.6
2003	61.24
2004	61.17
2005	60.93
2006	60.83
2007	60.87
2008	60.39
2009	60.27
2010	59.15
2011	59.62
2012	60.09
2013	60.85
2014	60.67
2015	60.77
2016	60.65
2017	60.54
2018	60.35
2019	59.87
2020	58.28