Year	Percent
1991	10.058
1992	10.114
1993	9.555
1994	9.733
1995	9.392
1996	9.248
1997	9.157
1998	8.835
1999	9.293
2000	9.543
2001	9.091
2002	8.148
2003	8.353
2004	8.009
2005	7.917
2006	7.847
2007	7.719
2008	8.927
2009	10.614
2010	14.911
2011	14.023
2012	13.025
2013	12.373
2014	12.531
2015	12.21
2016	12.279
2017	12.117
2018	12.137
2019	12.162
2020	12.128
2021	12.102
2022	12.064