| Year | Value | | 2022 | 47.964208993911 | | 2021 | 47.949146514936 | | 2020 | 47.927094726267 | | 2019 | 47.905632093654 | | 2018 | 47.887646234376 | | 2017 | 47.868991034683 | | 2016 | 47.850162749552 | | 2015 | 47.831043249677 | | 2014 | 47.809854663001 | | 2013 | 47.786466328355 | | 2012 | 47.761199433738 | | 2011 | 47.733460139535 | | 2010 | 47.701766583792 | | 2009 | 47.698061660171 | | 2008 | 47.720578795826 | | 2007 | 47.742812513815 | | 2006 | 47.773319774429 | | 2005 | 47.806677378774 | | 2004 | 47.836725573081 | | 2003 | 47.865599497568 | | 2002 | 47.891388789852 | | 2001 | 47.915230031239 | | 2000 | 47.933740652996 | | 1999 | 47.942612711512 | | 1998 | 47.95176792772 | | 1997 | 47.969410084187 | | 1996 | 47.992526437158 | | 1995 | 48.015844271701 | | 1994 | 48.040212141591 | | 1993 | 48.066054905266 | | 1992 | 48.087328793445 | | 1991 | 48.103329966615 | | 1990 | 48.092464112984 | | 1989 | 48.110403889333 | | 1988 | 48.184432026341 | | 1987 | 48.26215716749 | | 1986 | 48.342686844448 | | 1985 | 48.418252808139 | | 1984 | 48.488605754842 | | 1983 | 48.557727919534 | | 1982 | 48.619945079447 | | 1981 | 48.676791631983 | | 1980 | 48.733510795623 | | 1979 | 48.748880452099 | | 1978 | 48.720962196575 | | 1977 | 48.690034166056 | | 1976 | 48.656179160006 | | 1975 | 48.622769031527 | | 1974 | 48.591219885215 | | 1973 | 48.557694272879 | | 1972 | 48.522537768321 | | 1971 | 48.486486486486 | | 1970 | 48.416508904419 | | 1969 | 48.310016043625 | | 1968 | 48.190742168775 | | 1967 | 48.062598751034 | | 1966 | 47.93076555385 | | 1965 | 47.78875360758 | | 1964 | 47.636741346259 | | 1963 | 47.47768945416 | | 1962 | 47.308467012166 | | 1961 | 47.127489323828 | | 1960 | 47.024725865405 |
|