Year | Value | 2022 | 49.875538745712 | 2021 | 49.888618465579 | 2020 | 49.904638196861 | 2019 | 49.917753577603 | 2018 | 49.921928230752 | 2017 | 49.926455036628 | 2016 | 49.927675045936 | 2015 | 49.924424733 | 2014 | 49.92177096361 | 2013 | 49.917680393483 | 2012 | 49.911017038394 | 2011 | 49.896261099525 | 2010 | 49.884153773512 | 2009 | 49.885475613042 | 2008 | 49.883910714696 | 2007 | 49.881362418676 | 2006 | 49.881430079952 | 2005 | 49.882483918852 | 2004 | 49.877930461581 | 2003 | 49.869928851081 | 2002 | 49.856848259155 | 2001 | 49.844111091359 | 2000 | 49.835089135366 | 1999 | 49.819474218662 | 1998 | 49.801845625581 | 1997 | 49.784971232638 | 1996 | 49.765161137861 | 1995 | 49.745635985182 | 1994 | 49.729845560437 | 1993 | 49.713688349378 | 1992 | 49.699955431046 | 1991 | 49.692080205388 | 1990 | 49.717058740434 | 1989 | 49.766273574865 | 1988 | 49.803952389685 | 1987 | 49.836932174536 | 1986 | 49.873354991465 | 1985 | 49.925427035748 | 1984 | 50.011962065897 | 1983 | 50.123721383341 | 1982 | 50.241253925949 | 1981 | 50.398305939296 | 1980 | 50.567842814525 | 1979 | 50.691981434901 | 1978 | 50.778661543941 | 1977 | 50.853276337501 | 1976 | 50.940075841867 | 1975 | 51.04199356091 | 1974 | 51.164641461474 | 1973 | 51.319235619362 | 1972 | 51.487598193852 | 1971 | 51.650973165375 | 1970 | 51.827075519122 | 1969 | 52.108231767444 | 1968 | 52.489329533443 | 1967 | 52.896797346528 | 1966 | 53.332782118594 | 1965 | 53.794786003067 | 1964 | 54.284989858012 | 1963 | 54.81841985428 | 1962 | 55.402761795167 | 1961 | 56.027945564369 | 1960 | 56.315588347688 |
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