Year	Percent
1990	71.02
1991	71.29
1992	71.35
1993	71.63
1994	72.18
1995	72.49
1996	72.31
1997	72.07
1998	72.07
1999	71.87
2000	71.37
2001	70.69
2002	70.23
2003	69.83
2004	69.24
2005	69.52
2006	69.72
2007	70
2008	70.35
2009	70.04
2010	70.36
2011	70.38
2012	70.48
2013	70.61
2014	70.87
2015	70.89
2016	70.13
2017	69.25
2018	69.1
2019	68.81
2020	66.06