Year	Percent
1991	69.487
1992	69.096
1993	68.757
1994	68.743
1995	68.881
1996	68.829
1997	67.708
1998	66.837
1999	64.856
2000	64.202
2001	64.296
2002	64.971
2003	64.326
2004	63.435
2005	64.414
2006	64.626
2007	65.52
2008	65.816
2009	64.218
2010	63.616
2011	63.561
2012	63.617
2013	64.129
2014	64.859
2015	65.35
2016	66.314
2017	66.709
2018	66.827
2019	66.478
2020	66.114
2021	65.675
2022	65.219