Year | Value | 2023 | 50.999461437438 | 2022 | 51.028391196608 | 2021 | 51.062503010688 | 2020 | 51.08627905081 | 2019 | 51.112939797586 | 2018 | 51.184562219211 | 2017 | 51.30575695924 | 2016 | 51.450960578524 | 2015 | 51.560764289413 | 2014 | 51.626900164861 | 2013 | 51.699637505078 | 2012 | 51.777760239245 | 2011 | 51.855469066512 | 2010 | 51.929800969733 | 2009 | 52.003103576619 | 2008 | 52.087588462421 | 2007 | 52.187756844117 | 2006 | 52.292220061575 | 2005 | 52.399052301498 | 2004 | 52.504383457281 | 2003 | 52.598324153357 | 2002 | 52.684841810718 | 2001 | 52.775919254182 | 2000 | 52.867090694128 | 1999 | 52.945427494278 | 1998 | 52.862062525083 | 1997 | 52.633255470928 | 1996 | 52.412992393547 | 1995 | 52.187140227179 | 1994 | 51.943903009281 | 1993 | 51.828756865901 | 1992 | 51.848367086249 | 1991 | 51.876896625081 | 1990 | 51.920087688195 | 1989 | 51.963680932978 | 1988 | 52.020771016377 | 1987 | 52.001180338902 | 1986 | 51.897161484226 | 1985 | 51.803225794117 | 1984 | 51.718456175636 | 1983 | 51.714956213916 | 1982 | 51.786869929376 | 1981 | 51.857772577191 | 1980 | 51.925602896046 | 1979 | 51.990065190119 | 1978 | 51.959423724177 | 1977 | 51.845918580446 | 1976 | 51.757119315854 | 1975 | 51.739107350714 |
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