Year	Percent
1990	71.15
1991	71.36
1992	71.57
1993	71.81
1994	71.89
1995	71.87
1996	71.95
1997	72.04
1998	72.05
1999	72.07
2000	72.12
2001	72.2
2002	72.21
2003	72.19
2004	72.16
2005	72.12
2006	71.1
2007	70.06
2008	68.99
2009	67.9
2010	66.79
2011	65.66
2012	64.5
2013	64.48
2014	64.42
2015	64.36
2016	64.35
2017	64.29
2018	64.18
2019	64.07