Year | Value | 2022 | 50.225875347874 | 2021 | 50.180346990546 | 2020 | 50.144383220907 | 2019 | 50.118857040052 | 2018 | 50.086994601787 | 2017 | 50.041612842285 | 2016 | 49.994582537196 | 2015 | 49.955775663582 | 2014 | 49.923641610583 | 2013 | 49.888553356964 | 2012 | 49.851552827305 | 2011 | 49.812006244725 | 2010 | 49.770729563434 | 2009 | 49.730271284309 | 2008 | 49.690226206039 | 2007 | 49.64769124115 | 2006 | 49.602603716695 | 2005 | 49.554453527566 | 2004 | 49.503302178733 | 2003 | 49.506530628449 | 2002 | 49.571082139989 | 2001 | 49.642999298309 | 2000 | 49.718996739026 | 1999 | 49.7970063215 | 1998 | 49.87883027359 | 1997 | 49.965664724313 | 1996 | 50.058580460262 | 1995 | 50.160187806394 | 1994 | 50.211230623517 | 1993 | 50.203965670317 | 1992 | 50.195103463235 | 1991 | 50.185705597131 | 1990 | 50.17637538885 | 1989 | 50.166029973553 | 1988 | 50.153056530205 | 1987 | 50.134931853744 | 1986 | 50.11494194285 | 1985 | 50.097760421106 | 1984 | 50.082981153477 | 1983 | 50.065760169105 | 1982 | 50.04664871398 | 1981 | 50.02461029269 | 1980 | 49.998133890678 | 1979 | 49.936400591475 | 1978 | 49.847205310499 | 1977 | 49.76309582437 | 1976 | 49.678468570078 | 1975 | 49.595422008125 | 1974 | 49.511937321143 | 1973 | 49.42484943141 | 1972 | 49.333256190114 | 1971 | 49.31050491549 | 1970 | 49.362230797172 | 1969 | 49.418418031761 | 1968 | 49.47449559454 | 1967 | 49.526511844479 | 1966 | 49.570966634753 | 1965 | 49.60927401898 | 1964 | 49.64710204713 | 1963 | 49.710020980049 | 1962 | 49.800722186957 | 1961 | 49.851242404729 | 1960 | 49.855810071685 |
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