Year | Value | 2021 | 48.825382629747 | 2020 | 48.836245873214 | 2019 | 48.847836224431 | 2018 | 48.864922781132 | 2017 | 48.876531399869 | 2016 | 48.679672211909 | 2015 | 48.606942375294 | 2014 | 48.500125475146 | 2013 | 48.537677902736 | 2012 | 48.524578756334 | 2011 | 48.539263963832 | 2010 | 48.496237447544 | 2009 | 48.487724660718 | 2008 | 48.383885592516 | 2007 | 48.277477593505 | 2006 | 48.128266024865 | 2005 | 47.937591205873 | 2004 | 47.867744303542 | 2003 | 47.733941231209 | 2002 | 48.600898064113 | 2001 | 48.467757551658 | 2000 | 48.293236948296 | 1999 | 48.304747365367 | 1998 | 48.073790247183 | 1997 | 48.01611141282 | 1996 | 47.291645282757 | 1995 | 47.241733424065 | 1994 | 47.174488797435 | 1993 | 46.907481565633 | 1992 | 46.895606064648 | 1991 | 46.875560269227 | 1990 | 46.695975351618 | 1989 | 46.241911178878 | 1988 | 45.775888858705 | 1987 | 45.304364785827 | 1986 | 44.731089690603 | 1985 | 44.193189734775 | 1984 | 43.224439736742 | 1983 | 42.556813350948 | 1982 | 41.859218114262 | 1981 | 41.214834749486 | 1980 | 40.847750397964 | 1979 | 40.52424671085 | 1978 | 40.26906147759 | 1977 | 39.849923806459 | 1976 | 39.384821371802 | 1975 | 39.901407481125 | 1974 | 39.559905576381 | 1973 | 39.064174253073 | 1972 | 38.667935243251 | 1971 | 38.303650303191 | 1970 | 38.061080276822 | 1969 | 37.734772289058 | 1968 | 37.439108765033 | 1967 | 37.191241133441 | 1966 | 36.930063229474 | 1965 | 36.678919058884 | 1964 | 36.418258040405 | 1963 | 36.194034622664 | 1962 | 35.974473223128 | 1961 | 35.767580228448 |
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