Year | Value | 2022 | 34.522175733485 | 2021 | 34.044044744893 | 2020 | 33.585407365205 | 2019 | 33.134340462831 | 2018 | 32.688069838368 | 2017 | 32.256513656257 | 2016 | 31.838235083597 | 2015 | 31.439924748752 | 2014 | 31.081661301421 | 2013 | 30.827667943455 | 2012 | 30.591798657013 | 2011 | 30.335538732206 | 2010 | 30.040651554812 | 2009 | 29.687244144617 | 2008 | 29.352722857637 | 2007 | 28.996468914855 | 2006 | 28.754168517597 | 2005 | 28.459494807086 | 2004 | 28.190229451532 | 2003 | 27.950343763263 | 2002 | 27.726757747036 | 2001 | 27.488298924843 | 2000 | 27.232285742805 | 1999 | 26.982591970852 | 1998 | 26.741732297971 | 1997 | 26.498825094032 | 1996 | 26.27754434286 | 1995 | 26.090222375553 | 1994 | 25.797098203258 | 1993 | 25.462169623102 | 1992 | 25.130224937027 | 1991 | 24.817718428255 | 1990 | 24.505473358164 | 1989 | 24.13344935737 | 1988 | 23.737395676639 | 1987 | 23.320987074258 | 1986 | 22.899427992467 | 1985 | 22.468394934191 | 1984 | 22.039968001224 | 1983 | 21.648972732612 | 1982 | 21.31930096195 | 1981 | 21.028751259769 | 1980 | 20.710591683996 | 1979 | 20.402448872097 | 1978 | 20.129821446531 | 1977 | 19.860024600014 | 1976 | 19.596963921025 | 1975 | 19.343103307405 | 1974 | 19.041532898186 | 1973 | 18.734509999047 | 1972 | 18.384633812204 | 1971 | 18.022924166929 | 1970 | 17.676165113022 | 1969 | 17.129259972792 | 1968 | 16.574753705608 | 1967 | 16.083317209193 | 1966 | 15.663929390951 | 1965 | 15.262792703743 | 1964 | 14.877156140615 | 1963 | 14.501367995436 | 1962 | 14.13600566128 | 1961 | 13.788918698273 | 1960 | 13.449720908474 |
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