Year	Percent
1991	30.156
1992	31.24
1993	30.522
1994	30.062
1995	29.539
1996	27.869
1997	27.956
1998	27.366
1999	26.119
2000	25.991
2001	25.407
2002	25.483
2003	24.856
2004	25.27
2005	24.366
2006	23.228
2007	24.262
2008	25.221
2009	26.117
2010	24.942
2011	24.222
2012	24.294
2013	25.049
2014	25.185
2015	24.712
2016	24.115
2017	23.582
2018	23.421
2019	23.298
2020	23.191
2021	23.094
2022	22.997