Year	Percent
1991	36.716
1992	36.885
1993	36.534
1994	36.497
1995	36.591
1996	36.299
1997	35.881
1998	35.389
1999	34.868
2000	34.488
2001	34.183
2002	33.915
2003	33.907
2004	35.699
2005	35.622
2006	34.345
2007	33.098
2008	33.313
2009	33.853
2010	34.199
2011	34.607
2012	35.094
2013	36.358
2014	37.575
2015	37.49
2016	37.324
2017	37.242
2018	37.214
2019	37.134
2020	37.015
2021	36.894
2022	36.742