Year	Percent
1991	66.364
1992	65.639
1993	64.727
1994	63.961
1995	63.608
1996	63.473
1997	63.762
1998	64.185
1999	64.602
2000	64.878
2001	66.713
2002	64.542
2003	65.595
2004	64.948
2005	65.132
2006	65.121
2007	66.026
2008	66.538
2009	67.379
2010	67.977
2011	68.471
2012	68.965
2013	69.071
2014	69.05
2015	68.93
2016	68.733
2017	68.637
2018	68.536
2019	68.43
2020	68.339
2021	68.294
2022	68.267