Year	Percent
1991	58.87
1992	58.98
1993	58.72
1994	59.71
1995	60.38
1996	60.76
1997	60.9
1998	56.48
1999	56.8
2000	58.46
2001	58.86
2002	59.84
2003	59.23
2004	59.92
2005	59.84
2006	59.87
2007	59.98
2008	59.46
2009	58.49
2010	58.54
2011	58.91
2012	59.28
2013	59.45
2014	60.19
2015	60.47
2016	60.51
2017	60.83
2018	60.61
2019	60.89
2020	60.06