Year	Percent
1991	63.231
1992	62.834
1993	62.736
1994	62.656
1995	62.469
1996	62.348
1997	62.136
1998	61.574
1999	60.971
2000	60.65
2001	60.586
2002	59.867
2003	60.058
2004	60.542
2005	60.321
2006	60.828
2007	61.138
2008	61.52
2009	61.191
2010	62.077
2011	59.711
2012	60.529
2013	61.451
2014	61.794
2015	61.892
2016	61.843
2017	61.704
2018	61.517
2019	61.303
2020	61.057
2021	60.76
2022	60.438