Year	Percent
1990	61.18
1991	61.18
1992	61.34
1993	61.3
1994	61.39
1995	61.44
1996	61.37
1997	61.23
1998	61.16
1999	61.04
2000	60.5
2001	60.21
2002	60.09
2003	60.24
2004	60.34
2005	60.45
2006	60.58
2007	60.71
2008	60.84
2009	60.64
2010	60.76
2011	60.95
2012	60.93
2013	60.88
2014	60.8
2015	60.74
2016	60.72
2017	60.72
2018	60.72
2019	60.69