Year	Percent
1991	60.744
1992	60.733
1993	60.725
1994	60.725
1995	60.749
1996	60.738
1997	60.752
1998	60.728
1999	60.751
2000	59.389
2001	57.9
2002	56.433
2003	54.874
2004	53.315
2005	51.772
2006	51.884
2007	52.023
2008	52.218
2009	51.428
2010	51.682
2011	51.957
2012	52.195
2013	52.405
2014	52.602
2015	52.785
2016	52.938
2017	52.895
2018	52.848
2019	52.801
2020	52.751
2021	52.697
2022	52.639