Year	Percent
1991	11.625
1992	9.987
1993	10.224
1994	11.067
1995	11.315
1996	10.322
1997	10.435
1998	9.662
1999	9.78
2000	9.46
2001	9.779
2002	9.51
2003	8.632
2004	9.653
2005	9.746
2006	9.918
2007	10.054
2008	10.087
2009	10.499
2010	11.48
2011	11.585
2012	11.718
2013	12.263
2014	12.695
2015	13.389
2016	13.263
2017	13.295
2018	13.212
2019	13.14
2020	13.106
2021	13.075
2022	13.042