Year	Percent
1991	55.406
1992	55.176
1993	54.396
1994	53.581
1995	53.612
1996	54.633
1997	54.755
1998	55.726
1999	56.236
2000	55.964
2001	56.857
2002	57.522
2003	56.879
2004	56.412
2005	56.432
2006	57.069
2007	57.391
2008	59.001
2009	58.851
2010	56.807
2011	57.676
2012	58.055
2013	58.245
2014	58.925
2015	59.33
2016	59.735
2017	59.686
2018	59.669
2019	59.675
2020	59.626
2021	59.52
2022	59.377