Year	Percent
1991	13.448
1992	13.046
1993	12.79
1994	12.932
1995	13.329
1996	12.638
1997	12.438
1998	12.315
1999	11.936
2000	12.03
2001	14.024
2002	13.978
2003	13.473
2004	14.608
2005	13.531
2006	13.539
2007	13.43
2008	13.133
2009	13.131
2010	13.039
2011	12.964
2012	12.275
2013	12.425
2014	12.056
2015	11.754
2016	11.933
2017	12.036
2018	11.999
2019	11.94
2020	11.893
2021	11.88
2022	11.836