Year	Percent
1991	24.023
1992	26.138
1993	24.088
1994	24.052
1995	24.448
1996	21.97
1997	21.413
1998	19.594
1999	19.36
2000	19.116
2001	18.253
2002	16.897
2003	16.772
2004	17.916
2005	16.998
2006	15.773
2007	15.192
2008	15.296
2009	15.571
2010	15.291
2011	15.265
2012	14.379
2013	13.892
2014	13.685
2015	13.303
2016	12.93
2017	13.303
2018	13.321
2019	13.264
2020	13.244
2021	13.225
2022	13.206