Year	%
1979	11.1
1986	11.1
1992	11.4
1997	10.7
2001	10.4
2002	10.3
2003	10
2004	9.8
2005	9.7
2006	9.9
2007	10
2008	9.8
2009	9.5
2010	9.7
2011	9.8
2012	9.9
2013	10.5
2014	10.4
2015	10.6
2016	10.6
2017	11
2018	10.9
2019	11
2020	11
2021	10.9