Year | Value | 2021 | 44.129061943906 | 2020 | 44.084702709119 | 2019 | 44.026473278644 | 2018 | 43.954663831159 | 2017 | 43.818082865076 | 2016 | 43.720343246969 | 2015 | 43.619577906091 | 2014 | 43.498573788896 | 2013 | 43.384182452252 | 2012 | 43.192803007771 | 2011 | 43.177001277517 | 2010 | 43.013920250708 | 2009 | 42.844756939628 | 2008 | 42.629658424975 | 2007 | 42.509226347608 | 2006 | 42.341429788615 | 2005 | 42.22700738056 | 2004 | 41.883292186181 | 2003 | 42.076461463177 | 2002 | 41.823397028174 | 2001 | 41.720700450029 | 2000 | 41.566434110342 | 1999 | 41.42738332089 | 1998 | 41.221601075093 | 1997 | 41.120555418483 | 1996 | 40.950018179754 | 1995 | 40.78711316047 | 1994 | 40.515441494071 | 1993 | 40.245413106385 | 1992 | 40.766681928317 | 1991 | 40.547980260433 | 1990 | 40.419038781965 | 1989 | 40.335836184642 | 1988 | 40.198180703496 | 1987 | 39.988458280206 | 1986 | 39.886582215107 | 1985 | 39.685836402706 | 1984 | 39.471625673971 | 1983 | 39.435761572916 | 1982 | 39.378133424703 | 1981 | 39.337696333194 | 1980 | 39.287351095703 | 1979 | 39.244458138951 | 1978 | 39.223837339407 | 1977 | 39.151346972221 | 1976 | 39.131530680257 | 1975 | 39.099773802108 | 1974 | 39.048724853795 | 1973 | 39.055600218327 | 1972 | 39.039595293892 | 1971 | 39.00779715037 | 1970 | 38.931456201275 | 1969 | 38.917949399966 | 1968 | 38.877217290687 | 1967 | 38.811419268007 | 1966 | 38.801511457642 | 1965 | 38.779790488765 | 1964 | 38.772169096176 | 1963 | 38.76954394984 | 1962 | 38.733638722534 | 1961 | 38.724323687148 |
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