| Year | Value | | 2022 | 47.476739398309 | | 2021 | 47.427525079006 | | 2020 | 47.376271584211 | | 2019 | 47.285271947546 | | 2018 | 47.150545929805 | | 2017 | 47.007587573593 | | 2016 | 46.898533808132 | | 2015 | 46.822098844033 | | 2014 | 46.757234166536 | | 2013 | 46.702914000343 | | 2012 | 46.659060908064 | | 2011 | 46.624866565368 | | 2010 | 46.582853623825 | | 2009 | 46.537789460433 | | 2008 | 46.497224031814 | | 2007 | 46.483148263356 | | 2006 | 46.489627677546 | | 2005 | 46.491966261695 | | 2004 | 46.502554165933 | | 2003 | 46.525980184729 | | 2002 | 46.555276819118 | | 2001 | 46.589937283636 | | 2000 | 46.609114474646 | | 1999 | 46.586671302702 | | 1998 | 46.549438152085 | | 1997 | 46.528290737184 | | 1996 | 46.529794308099 | | 1995 | 46.559859579081 | | 1994 | 46.601166746966 | | 1993 | 46.642130339875 | | 1992 | 46.744084742671 | | 1991 | 46.82552102129 | | 1990 | 46.795834145087 | | 1989 | 46.736035335676 | | 1988 | 46.683094103179 | | 1987 | 46.625457289692 | | 1986 | 46.564406913178 | | 1985 | 46.516081589637 | | 1984 | 46.472979782656 | | 1983 | 46.428405394384 | | 1982 | 46.386255211071 | | 1981 | 46.344853301458 | | 1980 | 46.301548494465 | | 1979 | 46.257803052587 | | 1978 | 46.217605499122 | | 1977 | 46.17336502847 | | 1976 | 46.123432878974 | | 1975 | 46.066624345877 | | 1974 | 46.008652257568 | | 1973 | 45.948670177998 | | 1972 | 45.883788320026 | | 1971 | 45.819155451653 | | 1970 | 45.755319937827 | | 1969 | 45.654494981849 | | 1968 | 45.507807522863 | | 1967 | 45.363900947231 | | 1966 | 45.213155379658 | | 1965 | 45.050557119018 | | 1964 | 44.880508935016 | | 1963 | 44.705831102381 | | 1962 | 44.520974875016 | | 1961 | 44.33416609703 | | 1960 | 44.153673370201 |
|