Year	Percent
1992	12.2
1996	11.3
1999	10.9
2000	11
2001	11.1
2002	11.1
2003	11.7
2004	11.1
2005	11.5
2008	11.4
2009	11.5
2010	11.4
2011	11.7
2012	12
2013	12
2014	12
2015	12.5
2016	12.6