Year	Percent
1991	64.457
1992	64.352
1993	64.91
1994	63.719
1995	63.202
1996	62.17
1997	63.354
1998	63.847
1999	63.11
2000	63.162
2001	62.992
2002	62.386
2003	61.824
2004	60.781
2005	60.817
2006	60.549
2007	60.172
2008	59.533
2009	59.829
2010	59.004
2011	58.478
2012	58.084
2013	57.364
2014	56.725
2015	56.933
2016	57.365
2017	57.307
2018	57.25
2019	57.184
2020	57.108
2021	57.026
2022	56.941