Year	Percent
1990	63.24
1991	62.86
1992	62.73
1993	62.5
1994	62.18
1995	61.76
1996	61.2
1997	61.56
1998	60.43
1999	59.23
2000	59
2001	58.1
2002	56.84
2003	58.84
2004	58.91
2005	58.62
2006	60.58
2007	60.67
2008	61.35
2009	60.88
2010	60.53
2011	61.2
2012	61.27
2013	61.28
2014	61.15
2015	62.2
2016	63
2017	63.76
2018	63.83
2019	63.5
2020	62.9