Year	Percent
1991	55.817
1992	58.366
1993	60.792
1994	62.462
1995	64.622
1996	66.379
1997	68.85
1998	69.811
1999	67.914
2000	67.7
2001	67.111
2002	66.779
2003	67.208
2004	66.818
2005	66.371
2006	66.995
2007	67.545
2008	66.571
2009	66.544
2010	66.282
2011	65.605
2012	65.52
2013	65.678
2014	66.121
2015	66.665
2016	67.044
2017	67.014
2018	66.982
2019	66.949
2020	66.917
2021	66.883
2022	66.849