Year	Percent
1991	70.749
1992	68.349
1993	67.949
1994	65.235
1995	64.705
1996	66.218
1997	63.13
1998	67.567
1999	64.153
2000	66.295
2001	64.259
2002	65.148
2003	64.113
2004	62.189
2005	60.738
2006	64.606
2007	65.163
2008	63.643
2009	60.874
2010	63.483
2011	63.774
2012	62.744
2013	62.871
2014	62.641
2015	60.912
2016	62.088
2017	62.369
2018	62.255
2019	62.143
2020	62.01
2021	61.814
2022	61.619