Year	Percent
1991	30.551
1992	29.135
1993	29.895
1994	31.314
1995	34.346
1996	35.066
1997	34.666
1998	34.298
1999	33.913
2000	33.272
2001	33.034
2002	31.091
2003	31.826
2004	31.979
2005	31.996
2006	32.365
2007	32.905
2008	33.388
2009	33.523
2010	31.176
2011	28.912
2012	28.125
2013	26.949
2014	27.16
2015	26.544
2016	24.699
2017	24.19
2018	23.833
2019	23.521
2020	23.217
2021	22.908
2022	22.591