Year	Percent
1991	61.18
1992	60.505
1993	60.131
1994	59.703
1995	59.703
1996	59.64
1997	59.557
1998	59.43
1999	58.357
2000	57.26
2001	56.111
2002	54.922
2003	53.698
2004	52.455
2005	51.21
2006	49.999
2007	48.789
2008	47.579
2009	46.371
2010	45.174
2011	44.015
2012	42.87
2013	41.745
2014	40.65
2015	39.593
2016	38.558
2017	38.383
2018	38.211
2019	38.023
2020	37.884
2021	37.721
2022	37.536