Year	Percent
1991	64.98
1992	64.89
1993	64.71
1994	64.65
1995	64.75
1996	64.8
1997	64.86
1998	64.92
1999	64.91
2000	64.91
2001	64.93
2002	64.8
2003	64.66
2004	64.56
2005	64.52
2006	64.59
2007	64.65
2008	64.64
2009	64.26
2010	64.06
2011	63.99
2012	63.89
2013	63.76
2014	63.69
2015	63.6
2016	63.57
2017	63.59
2018	63.61
2019	63.59
2020	60.93