Year | Value | 2022 | 49.344793964873 | 2021 | 49.328345181299 | 2020 | 49.313219725817 | 2019 | 49.298363047178 | 2018 | 49.282400110989 | 2017 | 49.266882802811 | 2016 | 49.254996676361 | 2015 | 49.244791775823 | 2014 | 49.236826466672 | 2013 | 49.225374480451 | 2012 | 49.208140205547 | 2011 | 49.191475166559 | 2010 | 49.170115451562 | 2009 | 49.145267273001 | 2008 | 49.113590852821 | 2007 | 49.078966074402 | 2006 | 49.055152038493 | 2005 | 49.031582084745 | 2004 | 48.999833522731 | 2003 | 48.949193296123 | 2002 | 48.895864999309 | 2001 | 48.847792806204 | 2000 | 48.812477015145 | 1999 | 48.934362609947 | 1998 | 49.144183647594 | 1997 | 49.216669335881 | 1996 | 49.200180382876 | 1995 | 49.148626472961 | 1994 | 49.087637698898 | 1993 | 49.047727916206 | 1992 | 49.006508070935 | 1991 | 48.982748305725 | 1990 | 48.967329624737 | 1989 | 48.963456606653 | 1988 | 48.965414375305 | 1987 | 48.96680839151 | 1986 | 48.96489607414 | 1985 | 48.964771753799 | 1984 | 48.971179621041 | 1983 | 48.976560911294 | 1982 | 48.984749106962 | 1981 | 48.989282123549 | 1980 | 48.989434143435 | 1979 | 48.999925023035 | 1978 | 49.02020311954 | 1977 | 49.045497391166 | 1976 | 49.074954217618 | 1975 | 49.104569888212 | 1974 | 49.12660449187 | 1973 | 49.132011542183 | 1972 | 49.129574191662 | 1971 | 49.12879315651 | 1970 | 49.12983559982 | 1969 | 49.131764474488 | 1968 | 49.136492829873 | 1967 | 49.144761494599 | 1966 | 49.152107690061 | 1965 | 49.15902897198 | 1964 | 49.168039252606 | 1963 | 49.179092940565 | 1962 | 49.192071063183 | 1961 | 49.206338280239 | 1960 | 49.222599761667 |
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