Year	Percent
1991	63.966
1992	63.274
1993	64.203
1994	63.106
1995	63.661
1996	62.993
1997	62.202
1998	61.531
1999	61.353
2000	60.862
2001	60.918
2002	61.047
2003	60.812
2004	60.506
2005	60.194
2006	59.796
2007	59.108
2008	58.564
2009	58.224
2010	57.873
2011	57.241
2012	57.147
2013	56.898
2014	56.45
2015	56.098
2016	55.768
2017	55.715
2018	55.658
2019	55.593
2020	55.523
2021	55.455
2022	55.386