Year	Percent
1991	35.039
1992	34.903
1993	34.861
1994	38.834
1995	34.76
1996	37.392
1997	33.752
1998	33.994
1999	33.174
2000	35.18
2001	35.13
2002	35.145
2003	35.334
2004	35.098
2005	35.193
2006	35.144
2007	34.88
2008	34.694
2009	34.782
2010	34.899
2011	34.884
2012	34.891
2013	34.844
2014	34.785
2015	34.746
2016	34.654
2017	34.85
2018	34.854
2019	34.76
2020	34.663
2021	34.563
2022	34.465