Year	Percent
1991	62.829
1992	63.255
1993	62.985
1994	62.734
1995	62.626
1996	62.444
1997	62.397
1998	62.151
1999	62.05
2000	61.952
2001	62.342
2002	61.868
2003	61.747
2004	63.385
2005	62.552
2006	61.741
2007	60.96
2008	60.171
2009	59.383
2010	58.601
2011	57.818
2012	57.049
2013	56.254
2014	55.459
2015	55.92
2016	55.634
2017	55.604
2018	55.563
2019	55.517
2020	55.411
2021	55.315
2022	55.221