Year	Percent
1990	72.43
1991	72.46
1992	72.48
1993	72.57
1994	72.63
1995	72.66
1996	72.64
1997	72.58
1998	72.49
1999	72.37
2000	72.22
2001	72.03
2002	71.82
2003	71.88
2004	71.89
2005	71.85
2006	71.76
2007	71.62
2008	71.45
2009	71.25
2010	71.05
2011	70.87
2012	70.85
2013	70.81
2014	70.78
2015	70.8
2016	70.81
2017	70.81
2018	70.79
2019	70.76
2020	69.98