Year | Value | 2021 | 14.778666634248 | 2020 | 15.100339287465 | 2019 | 15.503752801329 | 2018 | 15.995687579263 | 2017 | 16.306909348576 | 2016 | 16.549259057854 | 2015 | 17.053799632147 | 2014 | 17.331315388353 | 2013 | 17.558558847151 | 2012 | 17.845363108955 | 2011 | 18.169586287514 | 2010 | 18.375226656287 | 2009 | 18.618426455873 | 2008 | 18.839712615948 | 2007 | 19.152642552721 | 2006 | 19.516062136628 | 2005 | 19.914677160121 | 2004 | 20.2501530329 | 2003 | 20.579630597359 | 2002 | 21.124182116651 | 2001 | 21.655127923587 | 2000 | 22.178917478054 | 1999 | 22.688641867772 | 1998 | 23.148884319965 | 1997 | 23.614198585072 | 1996 | 24.1063611935 | 1995 | 24.650755147455 | 1994 | 25.125268890864 | 1993 | 25.614786246477 | 1992 | 26.041359699986 | 1991 | 26.607079409149 | 1990 | 27.142541925303 | 1989 | 27.686857247408 | 1988 | 28.19092888628 | 1987 | 28.774778933208 | 1986 | 29.319501800901 | 1985 | 29.840373573259 | 1984 | 30.33674518101 | 1983 | 30.856617297299 | 1982 | 31.360546436003 | 1981 | 31.79878614873 | 1980 | 32.226635624734 | 1979 | 32.714121672262 | 1978 | 33.180043906446 | 1977 | 33.559040932868 | 1976 | 33.950348395616 | 1975 | 34.316752947294 | 1974 | 34.759961866201 | 1973 | 35.281161130816 | 1972 | 35.704981214087 | 1971 | 36.146255593347 | 1970 | 36.640325271592 | 1969 | 37.152336794264 | 1968 | 37.710477915233 | 1967 | 38.416511926203 | 1966 | 39.157469094561 | 1965 | 39.854686727007 | 1964 | 40.538898575489 | 1963 | 41.075026808077 | 1962 | 41.454937346379 | 1961 | 41.756209954358 | 1960 | 42.035256579037 |
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