Year	Percent
1991	64.406
1992	64.309
1993	64.35
1994	59.548
1995	57.008
1996	55.501
1997	55.615
1998	55.682
1999	55.46
2000	55.908
2001	57.449
2002	57.805
2003	57.948
2004	57.651
2005	58.211
2006	58.807
2007	59.605
2008	60.408
2009	60.209
2010	61.019
2011	61.294
2012	61.166
2013	61.647
2014	61.666
2015	61.615
2016	61.593
2017	61.604
2018	61.328
2019	60.948
2020	60.466
2021	59.852
2022	59.137