Year	Percent
1991	42.169
1992	42.443
1993	42.27
1994	42.581
1995	41.987
1996	41.585
1997	41.76
1998	41.704
1999	41.587
2000	40.96
2001	40.257
2002	40.303
2003	40.282
2004	40.183
2005	40.05
2006	40.184
2007	39.263
2008	38.83
2009	38.999
2010	38.62
2011	37.726
2012	36.636
2013	36.789
2014	36.697
2015	36.501
2016	36.047
2017	36.037
2018	35.951
2019	35.83
2020	35.677
2021	35.542
2022	35.369