Year	Percent
1991	72.028
1992	71.44
1993	71.999
1994	72.176
1995	73.119
1996	72.971
1997	72.861
1998	73.114
1999	73.016
2000	72.861
2001	72.678
2002	72.515
2003	72.334
2004	72.145
2005	71.92
2006	71.786
2007	71.629
2008	71.463
2009	71.303
2010	71.126
2011	70.948
2012	70.856
2013	70.792
2014	70.574
2015	70.374
2016	70.164
2017	70.169
2018	70.161
2019	70.144
2020	70.124
2021	70.108
2022	70.091