Year	Percent
1990	76.57
1991	76.62
1992	76.67
1993	76.72
1994	76.67
1995	76.56
1996	76.32
1997	76.05
1998	75.76
1999	75.46
2000	74.79
2001	74.16
2002	73.55
2003	72.97
2004	72.41
2005	71.88
2006	71.43
2007	71.01
2008	70.62
2009	70.24
2010	69.9
2011	69.76
2012	69.61
2013	69.43
2014	69.54
2015	69.56
2016	69.64
2017	69.75
2018	69.82
2019	69.87