Year	Percent
1990	60.78
1991	60.91
1992	61.07
1993	61.97
1994	62.77
1995	62.04
1996	60.61
1997	60.39
1998	62.23
1999	61.97
2000	61.43
2001	60.9
2002	60.34
2003	61.79
2004	60.46
2005	60.91
2006	61.36
2007	61.86
2008	61.74
2009	61.6
2010	59.93
2011	59.77
2012	60.43
2013	60.8
2014	59.57
2015	58.84
2016	59.52
2017	59.19
2018	58.93
2019	59.12
2020	52.43