Year	Percent
1991	80.449
1992	78.036
1993	76.33
1994	77.124
1995	77.681
1996	77.962
1997	78.11
1998	78.315
1999	77.005
2000	74.556
2001	73.239
2002	72.449
2003	72.161
2004	71.68
2005	71.197
2006	71.477
2007	70.462
2008	67.949
2009	68.597
2010	68.27
2011	65.026
2012	64.863
2013	64.535
2014	64.091
2015	63.259
2016	62.975
2017	62.448
2018	62.016
2019	61.553
2020	61.158
2021	61.381
2022	61.616