Year	Percent
1991	11.891
1992	11.704
1993	11.382
1994	11.176
1995	11.026
1996	10.896
1997	9.754
1998	9.768
1999	11.032
2000	11.853
2001	10.784
2002	10.556
2003	10.905
2004	11.636
2005	10.353
2006	9.224
2007	8.535
2008	7.373
2009	7.915
2010	8.001
2011	7.531
2012	7.305
2013	6.799
2014	6.39
2015	6.635
2016	6.936
2017	6.922
2018	6.927
2019	6.931
2020	6.935
2021	6.938
2022	6.941