Year	Percent
1991	38.621
1992	39.117
1993	38.926
1994	43.12
1995	40.029
1996	39.474
1997	35.255
1998	35.153
1999	35.2
2000	35.423
2001	39.907
2002	39.704
2003	39.914
2004	39.067
2005	37.08
2006	36.256
2007	35.083
2008	33.802
2009	33.68
2010	32.993
2011	32.773
2012	33.83
2013	34.199
2014	34.343
2015	35.978
2016	36.51
2017	36.547
2018	36.516
2019	36.435
2020	36.335
2021	36.25
2022	36.173