Year	Percent
1991	23.087
1992	23.889
1993	25.511
1994	25.547
1995	25.936
1996	26.269
1997	26.185
1998	25.691
1999	25.718
2000	26.176
2001	26.413
2002	26.724
2003	28.328
2004	28.749
2005	29.348
2006	30.056
2007	30.537
2008	31.078
2009	31.572
2010	32.044
2011	32.248
2012	32.102
2013	31.8
2014	31.394
2015	30.656
2016	30.546
2017	30.517
2018	30.379
2019	30.274
2020	30.185
2021	30.073
2022	29.995