Year	%
1997	11
1998	10.9
1999	11
2000	11.1
2001	11.2
2002	11.1
2003	10.4
2004	10.3
2005	10.1
2006	10.2
2007	9.9
2008	10.1
2009	10.5
2010	10.5
2011	10.5
2012	10.3
2013	10.3
2014	10.6
2015	11.1
2016	11.2
2017	11.2
2018	11.2
2019	11.1
2020	11.6