Year | Value | 2021 | 33.406217042559 | 2020 | 33.406060394533 | 2019 | 33.324672832192 | 2018 | 33.391709068495 | 2017 | 33.393527794956 | 2016 | 33.29657688597 | 2015 | 33.245967437343 | 2014 | 33.228935301696 | 2013 | 33.231642520514 | 2012 | 33.209247677895 | 2011 | 33.194086235962 | 2010 | 33.177597788668 | 2009 | 33.144173241325 | 2008 | 33.182763865828 | 2007 | 33.396408287792 | 2006 | 33.357952411027 | 2005 | 33.3220517866 | 2004 | 34.815694713907 | 2003 | 34.740570555858 | 2002 | 34.665821008796 | 2001 | 34.605340064581 | 2000 | 34.541072317114 | 1999 | 34.589796218684 | 1998 | 34.072848680548 | 1997 | 33.275052061018 | 1996 | 32.735600979846 | 1995 | 32.073625003897 | 1994 | 31.442644658724 | 1993 | 30.774094644249 | 1992 | 30.045338381027 | 1991 | 29.874401290549 | 1990 | 29.685762718205 | 1989 | 29.210589841826 | 1988 | 28.787936822958 | 1987 | 28.253830537946 | 1986 | 27.735473084018 | 1985 | 27.271114167445 | 1984 | 26.775360918136 | 1983 | 26.250819732003 | 1982 | 26.167051628196 | 1981 | 26.090646637384 | 1980 | 26.413853983038 | 1979 | 26.515134644489 | 1978 | 26.40797489451 | 1977 | 26.431847557016 | 1976 | 26.436835874555 | 1975 | 26.40556981284 | 1974 | 26.487075358335 | 1973 | 26.470150709544 | 1972 | 26.421242318241 | 1971 | 26.235428152004 | 1970 | 26.040260923708 | 1969 | 25.968910421716 | 1968 | 25.90379529443 | 1967 | 25.87199488343 | 1966 | 25.81195713269 | 1965 | 25.80964113637 | 1964 | 25.785055944673 | 1963 | 25.775791959395 | 1962 | 25.748890771378 | 1961 | 25.755660606773 |
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