Year | Value | 2022 | 18.363616339169 | 2021 | 18.568516287007 | 2020 | 18.75203613909 | 2019 | 18.938297142542 | 2018 | 19.130630992075 | 2017 | 19.314107570988 | 2016 | 19.495079972331 | 2015 | 19.673780302037 | 2014 | 19.848819333844 | 2013 | 20.016832205738 | 2012 | 20.186397836537 | 2011 | 20.360505519193 | 2010 | 20.565881371632 | 2009 | 20.837752914283 | 2008 | 21.121288464135 | 2007 | 21.420741494454 | 2006 | 21.729046756905 | 2005 | 22.047593723631 | 2004 | 22.390140499635 | 2003 | 22.744281627482 | 2002 | 23.111209798748 | 2001 | 23.503213553104 | 2000 | 23.840529387687 | 1999 | 24.057436150073 | 1998 | 24.278213088349 | 1997 | 24.500422109233 | 1996 | 24.724860781235 | 1995 | 24.961801138169 | 1994 | 25.208245357324 | 1993 | 25.455965972461 | 1992 | 25.702205305535 | 1991 | 25.97079943498 | 1990 | 26.256060420253 | 1989 | 26.512913388107 | 1988 | 26.767526746276 | 1987 | 27.050302921582 | 1986 | 27.344256706925 | 1985 | 27.611004138399 | 1984 | 27.848982010277 | 1983 | 28.092382346898 | 1982 | 28.348958993897 | 1981 | 28.624764833045 | 1980 | 28.942110903283 | 1979 | 29.236383283222 | 1978 | 29.528172794978 | 1977 | 29.819438836064 | 1976 | 30.104110364152 | 1975 | 30.391517986012 | 1974 | 30.734091588458 | 1973 | 31.092080247468 | 1972 | 31.45280831468 | 1971 | 31.821312660799 | 1970 | 32.223576402224 | 1969 | 32.677836014606 | 1968 | 33.148810052087 | 1967 | 33.647703983419 | 1966 | 34.161805373124 | 1965 | 34.664122436199 | 1964 | 35.179665412732 | 1963 | 35.696582055132 | 1962 | 36.214197858168 | 1961 | 36.715111843005 | 1960 | 37.21113157375 |
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