Year	Percent
1991	65.728
1992	66.307
1993	65.576
1994	66.117
1995	65.723
1996	65.393
1997	65.241
1998	64.483
1999	64.292
2000	63.925
2001	63.076
2002	62.836
2003	62.376
2004	61.949
2005	62.031
2006	62.223
2007	62.549
2008	62.319
2009	62.377
2010	61.989
2011	61.847
2012	61.433
2013	60.773
2014	60.106
2015	59.482
2016	59.169
2017	59.159
2018	58.808
2019	58.379
2020	57.962
2021	57.506
2022	57.047