Year	Percent
1991	24.539
1992	23.756
1993	23.564
1994	25.257
1995	26.308
1996	26.329
1997	26.346
1998	23.717
1999	21.781
2000	21.819
2001	22.617
2002	22.646
2003	22.684
2004	22.433
2005	22.505
2006	21.281
2007	21.503
2008	21.898
2009	21.209
2010	20.517
2011	20.293
2012	22.71
2013	20.84
2014	20.629
2015	20.656
2016	20.344
2017	20.212
2018	20.232
2019	20.267
2020	20.271
2021	20.302
2022	20.31