Year	Percent
1991	73.939
1992	73.262
1993	73.492
1994	73.012
1995	72.562
1996	73.077
1997	72.641
1998	72.571
1999	72.266
2000	71.343
2001	71.138
2002	70.92
2003	70.926
2004	70.917
2005	70.821
2006	70.776
2007	70.474
2008	70.408
2009	70.288
2010	70.081
2011	69.945
2012	69.79
2013	69.479
2014	69.335
2015	69.301
2016	69.061
2017	69.019
2018	68.979
2019	68.938
2020	68.897
2021	68.859
2022	68.82