| Year | Value | | 2022 | 3.3086205243952 | | 2021 | -4.1703363001753 | | 2020 | 0.31190496125083 | | 2019 | 1.1442833068893 | | 2018 | 0.46970429871412 | | 2017 | 0.088595469992426 | | 2016 | 1.297436099386 | | 2015 | 1.1863769374982 | | 2014 | 1.2984401779923 | | 2013 | 1.6193080985888 | | 2012 | 2.4533903303102 | | 2011 | 2.0849024560601 | | 2010 | 1.771832879264 | | 2009 | 3.0159499147579 | | 2008 | 5.3215170830262 | | 2007 | 4.1660028636093 | | 2006 | 3.1293891560754 | | 2005 | 2.3505112885718 | | 2004 | 1.2519166730553 | | 2003 | -1.4745328419194 | | 2002 | 0.9126398057768 | | 2001 | 2.6973558432636 | | 2000 | 1.7320422325426 | | 1999 | 0.79914845100393 | | 1998 | 3.3972122767729 | | 1997 | 3.3574421951607 | | 1996 | 4.0643184683903 | | 1995 | 3.0378134848112 | | 1994 | 3.1365869318362 | | 1993 | 2.5298067473268 | | 1992 | 3.0042563946205 | | 1991 | 2.8454828648656 | | 1990 | 3.889093607453 | | 1989 | 2.9357437345498 | | 1988 | 2.5377738673367 | | 1987 | 1.5038330579557 | | 1986 | 0.09449055706127 | | 1985 | 0.13664517070653 | | 1984 | 1.8902219856268 | | 1983 | 1.298744662244 | | 1982 | 4.3885936328951 | | 1981 | 4.8076890093413 | | 1980 | 1.2692342991651 | | 1979 | 1.2623924797707 | | 1978 | 1.2097007891598 | | 1977 | 1.3857234685649 | | 1976 | 1.347723377756 | | 1975 | 1.4602699158895 | | 1974 | 1.6641425915583 | | 1973 | 1.8686970802623 | | 1972 | 1.852208719579 | | 1971 | 1.8337876345183 | | 1970 | 1.5548987340134 | | 1969 | 1.5045295514528 | | 1968 | 1.7245263956258 | | 1967 | 2.2086787402843 | | 1966 | 2.486193006686 | | 1965 | 2.430051182605 | | 1964 | 2.5629737045239 | | 1963 | 2.5274954820648 | | 1962 | 2.7691046954406 | | 1961 | 3.344793406754 |
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