Year | Value | 2022 | 48.496950401467 | 2021 | 48.519024409084 | 2020 | 48.53120905935 | 2019 | 48.671208305495 | 2018 | 48.92868047682 | 2017 | 49.168834417045 | 2016 | 49.391966502514 | 2015 | 49.597480207659 | 2014 | 49.683871233031 | 2013 | 49.662352472357 | 2012 | 49.640280267584 | 2011 | 49.618596899618 | 2010 | 49.599103246727 | 2009 | 49.582994606287 | 2008 | 49.570618623037 | 2007 | 49.562625478002 | 2006 | 49.562699264216 | 2005 | 49.559362349355 | 2004 | 49.546176584447 | 2003 | 49.530801208576 | 2002 | 49.515299777406 | 2001 | 49.498291260366 | 2000 | 49.476860151802 | 1999 | 49.45332021967 | 1998 | 49.428182935514 | 1997 | 49.401553383026 | 1996 | 49.370526267258 | 1995 | 49.333424250689 | 1994 | 49.295087836253 | 1993 | 49.256990946885 | 1992 | 49.214784935255 | 1991 | 49.167978915296 | 1990 | 49.178952054985 | 1989 | 49.252815627391 | 1988 | 49.300492776126 | 1987 | 49.320764287631 | 1986 | 49.375636712102 | 1985 | 49.467141861006 | 1984 | 49.562423069215 | 1983 | 49.659992468595 | 1982 | 49.809763941823 | 1981 | 49.930464300273 | 1980 | 49.969058967467 | 1979 | 50.00864871868 | 1978 | 50.057941103944 | 1977 | 50.10135593387 | 1976 | 50.256723919439 | 1975 | 50.5025289922 | 1974 | 50.575035702349 | 1973 | 50.563478440884 | 1972 | 50.551065158532 | 1971 | 50.538851833456 | 1970 | 50.527271284508 | 1969 | 50.515379183354 | 1968 | 50.503273009529 | 1967 | 50.4909218492 | 1966 | 50.478084455684 | 1965 | 50.463700840022 | 1964 | 50.445420696992 | 1963 | 50.424572827643 | 1962 | 50.401446892951 | 1961 | 50.375736188788 | 1960 | 50.350593851705 |
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