Year | Value | 2022 | 31.324 | 2021 | 31.246 | 2020 | 31.191 | 2019 | 31.158 | 2018 | 31.147 | 2017 | 31.159 | 2016 | 31.193 | 2015 | 31.249 | 2014 | 31.328 | 2013 | 31.429 | 2012 | 31.553 | 2011 | 31.7 | 2010 | 31.87 | 2009 | 32.063 | 2008 | 32.256 | 2007 | 32.451 | 2006 | 32.646 | 2005 | 32.841 | 2004 | 33.037 | 2003 | 33.234 | 2002 | 33.431 | 2001 | 33.629 | 2000 | 33.827 | 1999 | 34.152 | 1998 | 34.503 | 1997 | 34.856 | 1996 | 35.21 | 1995 | 35.566 | 1994 | 35.924 | 1993 | 36.283 | 1992 | 36.643 | 1991 | 37.006 | 1990 | 37.37 | 1989 | 37.654 | 1988 | 37.923 | 1987 | 38.194 | 1986 | 38.464 | 1985 | 38.736 | 1984 | 39.007 | 1983 | 39.28 | 1982 | 39.554 | 1981 | 39.828 | 1980 | 40.102 | 1979 | 39.91 | 1978 | 39.646 | 1977 | 39.381 | 1976 | 39.118 | 1975 | 38.855 | 1974 | 38.592 | 1973 | 38.331 | 1972 | 38.07 | 1971 | 37.809 | 1970 | 37.55 | 1969 | 37.433 | 1968 | 37.36 | 1967 | 37.287 | 1966 | 37.214 | 1965 | 37.141 | 1964 | 37.068 | 1963 | 36.995 | 1962 | 36.922 | 1961 | 36.849 | 1960 | 36.777 |
|