Year	Percent
1991	40.604
1992	39.703
1993	39.68
1994	39.457
1995	39.201
1996	39.128
1997	39.187
1998	37.803
1999	37.978
2000	39.311
2001	38.273
2002	35.339
2003	35.096
2004	39.687
2005	34.467
2006	34.351
2007	33.996
2008	33.691
2009	33.719
2010	33.325
2011	32.947
2012	31.159
2013	31.056
2014	30.898
2015	30.971
2016	30.905
2017	30.937
2018	30.921
2019	30.903
2020	30.884
2021	30.864
2022	30.844