Year	Percent
1990	58.53
1991	58.69
1992	59.32
1993	60
1994	59.83
1995	59.63
1996	59.65
1997	61.07
1998	60.85
1999	60.09
2000	59.91
2001	59.29
2002	58.85
2003	59.19
2004	59.73
2005	60.58
2006	61.3
2007	61.37
2008	61.05
2009	60.94
2010	60.72
2011	60.75
2012	61.43
2013	61.24
2014	60.64
2015	60.76
2016	60.67
2017	60.48
2018	60.7
2019	61.42
2020	56.45