Year	%
1963	11.4
1964	11.3
1965	11.4
1966	11.3
1967	11.5
1968	11.7
1969	11.7
1970	11.6
1971	11.6
1972	11.6
1973	11.8
1974	12
1975	11.9
1976	11.9
1977	11.9
1978	12.1
1979	12
1980	12
1981	11.8
1982	11.5
1983	11.3
1984	11.3
1985	11.2
1986	11.2
1987	11.3
1988	11.1
1989	11
1990	11
1991	11.1
1992	11
1993	10.5
1994	10.6
1995	10.7
1996	10.5
1997	10.5
1998	10.7
1999	10.7
2000	10.7
2001	10.6
2002	10.6
2003	10.5
2004	10.7
2005	10.5
2006	10.4
2007	10.5
2008	10.5
2009	10.5
2010	10.6
2011	10.3
2012	10.3
2013	10.4
2014	10.2
2015	10.3
2016	10.3
2017	10.2
2018	10.3
2019	10.2
2020	10.6
2021	10.6