Year	Percent
1990	75.63
1991	75.67
1992	75.7
1993	75.71
1994	75.72
1995	75.71
1996	75.73
1997	75.75
1998	75.73
1999	75.67
2000	75.57
2001	75.01
2002	74.45
2003	73.88
2004	73.32
2005	72.79
2006	72.28
2007	72.01
2008	71.75
2009	71.48
2010	71.19
2011	70.87
2012	70.53
2013	70.16
2014	69.77
2015	69.35
2016	69.37
2017	69.32
2018	69.27
2019	69.21