Year	Percent
1991	43.597
1992	43.086
1993	40.855
1994	37.965
1995	38.725
1996	38.868
1997	40.333
1998	38.343
1999	38.406
2000	39.693
2001	39.829
2002	39.924
2003	40.474
2004	39.04
2005	39.044
2006	37.265
2007	34.121
2008	32.825
2009	36.727
2010	36.493
2011	35.888
2012	34.137
2013	34.098
2014	34.948
2015	37.595
2016	37.475
2017	37.368
2018	37.153
2019	36.919
2020	36.681
2021	36.452
2022	36.236