Year	Percent
1991	40.874
1992	40.422
1993	38.932
1994	38.399
1995	37.961
1996	37.452
1997	36.99
1998	37.009
1999	37.454
2000	36.745
2001	35.404
2002	35.574
2003	34.909
2004	35.661
2005	34.946
2006	35.519
2007	34.966
2008	36.184
2009	34.657
2010	34.272
2011	34.43
2012	32.642
2013	32.79
2014	32.657
2015	32.756
2016	32.443
2017	32.487
2018	32.447
2019	32.294
2020	32.137
2021	31.955
2022	31.798