Year	Percent
1991	20.158
1992	24.027
1993	27.889
1994	29.593
1995	29.656
1996	32.161
1997	32.373
1998	34.513
1999	30.597
2000	31.261
2001	32.152
2002	31.913
2003	32.171
2004	31.664
2005	31.215
2006	31.299
2007	31.068
2008	30.918
2009	30.884
2010	31.277
2011	31.233
2012	31.411
2013	30.321
2014	31.65
2015	31.506
2016	32.229
2017	31.919
2018	31.614
2019	31.311
2020	31.019
2021	30.722
2022	30.406