Year	Percent
1991	63.483
1992	63.26
1993	63.056
1994	62.568
1995	62.195
1996	62.049
1997	61.877
1998	61.713
1999	61.491
2000	61.225
2001	60.977
2002	60.667
2003	60.392
2004	60.132
2005	59.586
2006	59.502
2007	59.445
2008	59.4
2009	59.393
2010	59.294
2011	58.957
2012	58.634
2013	58.221
2014	57.828
2015	57.348
2016	56.833
2017	56.634
2018	56.379
2019	56.079
2020	55.746
2021	55.403
2022	55.015