Year	Percent
1991	32.191
1992	31.276
1993	30.611
1994	30.791
1995	31
1996	30.94
1997	31.314
1998	31.566
1999	31.618
2000	32.017
2001	32.003
2002	32.263
2003	31.993
2004	32.239
2005	32.054
2006	31.388
2007	30.96
2008	31.067
2009	30.054
2010	30.008
2011	29.773
2012	29.954
2013	29.893
2014	29.656
2015	29.315
2016	29.327
2017	29.406
2018	29.265
2019	29.068
2020	29.031
2021	28.878
2022	28.798