Year	Percent
1991	27.067
1992	24.633
1993	23.959
1994	21.263
1995	20.941
1996	20.295
1997	20.722
1998	20.745
1999	20.147
2000	18.838
2001	18.441
2002	17.189
2003	17.228
2004	17.128
2005	17.106
2006	17.443
2007	17.809
2008	17.821
2009	16.753
2010	16.127
2011	16.516
2012	16.112
2013	16.127
2014	16.512
2015	16.488
2016	16.885
2017	16.804
2018	16.505
2019	16.205
2020	15.9
2021	15.582
2022	15.295