Year	Percent
1991	43.77
1992	40.894
1993	38.071
1994	33.301
1995	32.465
1996	32.803
1997	33.789
1998	34.434
1999	34.008
2000	33.475
2001	29.125
2002	30.19
2003	28.778
2004	30.982
2005	33.173
2006	36.902
2007	35.377
2008	33.804
2009	32.531
2010	30.548
2011	32.205
2012	33.835
2013	35.205
2014	34.998
2015	34.762
2016	34.236
2017	33.987
2018	33.717
2019	33.515
2020	33.296
2021	33.059
2022	32.81