| Year | Value | | 2022 | 0.011246541169963 | | 2021 | 0.2570409219151 | | 2020 | 0.23651955779957 | | 2019 | 0.068899222152201 | | 2018 | 0.12309147954561 | | 2017 | 0.20249260582026 | | 2016 | 0.29479362583746 | | 2015 | 0.35497514594779 | | 2014 | 0.41074809911448 | | 2013 | 0.48119123830414 | | 2012 | 0.49575236668878 | | 2011 | 0.44791514404371 | | 2010 | 0.42134865482354 | | 2009 | 0.40590628691704 | | 2008 | 0.37512556474181 | | 2007 | 0.42891014375515 | | 2006 | 0.47692050349828 | | 2005 | 0.4807824891748 | | 2004 | 0.48906495556364 | | 2003 | 0.48335677592726 | | 2002 | 0.48783744746056 | | 2001 | 0.50404776022055 | | 2000 | 0.61185074900664 | | 1999 | 0.76182920473896 | | 1998 | 0.84236731376933 | | 1997 | 0.86716970473264 | | 1996 | 0.93299998969117 | | 1995 | 1.0089092327172 | | 1994 | 1.0163453890667 | | 1993 | 1.0008183853671 | | 1992 | 0.93706561811895 | | 1991 | 0.82587585670054 | | 1990 | 0.78335984523667 | | 1989 | 0.78508578711008 | | 1988 | 0.79129818888602 | | 1987 | 0.87590809258201 | | 1986 | 1.0347970905541 | | 1985 | 1.2262767180734 | | 1984 | 1.3926779010512 | | 1983 | 1.4970088164336 | | 1982 | 1.509282673142 | | 1981 | 1.4463074994874 | | 1980 | 1.3487117647391 | | 1979 | 1.2634194433269 | | 1978 | 1.2360715406651 | | 1977 | 1.245776518066 | | 1976 | 1.3089573834108 | | 1975 | 1.4185348174632 | | 1974 | 1.5081149054136 | | 1973 | 1.5552741744422 | | 1972 | 1.5339743032814 | | 1971 | 1.4446344591915 | | 1970 | 1.3253008361009 | | 1969 | 1.2288107096439 | | 1968 | 1.2006953417618 | | 1967 | 1.2236543090339 | | 1966 | 1.2416180985981 | | 1965 | 1.2554893123763 | | 1964 | 1.2431011897206 | | 1963 | 1.1870978860366 | | 1962 | 1.1953486825817 | | 1961 | 1.2959920781795 |
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