Year	Percent
1990	59.97
1991	61.25
1992	59.15
1993	58.9
1994	58.92
1995	58.46
1996	58.74
1997	59.35
1998	60.55
1999	60.62
2000	60.79
2001	61.43
2002	61.98
2003	61.97
2004	61.57
2005	61.99
2006	62.2
2007	62.29
2008	62.06
2009	61.26
2010	61.06
2011	60.38
2012	60.02
2013	59.2
2014	58.77
2015	58.62
2016	58.52
2017	59.02
2018	59.19
2019	59.27
2020	57.93