Year	Percent
1991	65.675
1992	65.537
1993	65.299
1994	64.752
1995	64.648
1996	64.841
1997	64.639
1998	64.377
1999	64.092
2000	63.005
2001	62.828
2002	62.592
2003	62.405
2004	62.141
2005	62.138
2006	61.858
2007	61.59
2008	61.505
2009	61.331
2010	61.057
2011	60.885
2012	60.651
2013	60.321
2014	60.058
2015	59.926
2016	59.724
2017	59.652
2018	59.58
2019	59.508
2020	59.436
2021	59.364
2022	59.292