Year	Percent
1991	40.803
1992	38.937
1993	38.02
1994	37.696
1995	39.438
1996	39.142
1997	39.521
1998	40.044
1999	39.917
2000	40.196
2001	39.12
2002	39.635
2003	39.52
2004	38.655
2005	38.296
2006	38.457
2007	38.912
2008	38.685
2009	37.287
2010	35.896
2011	35.757
2012	35.673
2013	35.835
2014	34.478
2015	33.963
2016	34.568
2017	34.692
2018	34.434
2019	34.141
2020	33.931
2021	33.77
2022	33.656