Year | Value | 2022 | 18.248 | 2021 | 18.347 | 2020 | 18.438 | 2019 | 18.518 | 2018 | 18.589 | 2017 | 18.65 | 2016 | 18.7 | 2015 | 18.741 | 2014 | 18.782 | 2013 | 18.822 | 2012 | 18.863 | 2011 | 18.904 | 2010 | 19.063 | 2009 | 19.242 | 2008 | 19.422 | 2007 | 19.604 | 2006 | 19.787 | 2005 | 19.878 | 2004 | 19.955 | 2003 | 20.033 | 2002 | 20.112 | 2001 | 20.19 | 2000 | 20.522 | 1999 | 20.897 | 1998 | 21.276 | 1997 | 21.66 | 1996 | 22.049 | 1995 | 22.325 | 1994 | 22.586 | 1993 | 22.848 | 1992 | 23.113 | 1991 | 23.38 | 1990 | 23.418 | 1989 | 23.438 | 1988 | 23.458 | 1987 | 23.478 | 1986 | 23.498 | 1985 | 23.646 | 1984 | 23.805 | 1983 | 23.965 | 1982 | 24.126 | 1981 | 24.288 | 1980 | 24.337 | 1979 | 24.377 | 1978 | 24.417 | 1977 | 24.457 | 1976 | 24.497 | 1975 | 24.389 | 1974 | 24.269 | 1973 | 24.149 | 1972 | 24.029 | 1971 | 23.91 | 1970 | 24.346 | 1969 | 24.839 | 1968 | 25.338 | 1967 | 25.845 | 1966 | 26.358 | 1965 | 27.108 | 1964 | 27.893 | 1963 | 28.693 | 1962 | 29.506 | 1961 | 30.332 | 1960 | 30.939 |
|