Year | Value | 2021 | 67.871386959444 | 2020 | 68.021510194936 | 2019 | 66.34978041676 | 2018 | 68.397506609904 | 2017 | 69.564302487116 | 2016 | 69.17992381806 | 2015 | 67.324669504817 | 2014 | 67.404212413175 | 2013 | 68.530136679364 | 2012 | 68.122339233699 | 2011 | 67.45193815819 | 2010 | 67.193143625364 | 2009 | 67.225184853238 | 2008 | 67.176786914631 | 2007 | 67.129733363209 | 2006 | 67.098364328927 | 2005 | 67.194712077078 | 2004 | 67.311225632982 | 2003 | 69.182164463365 | 2002 | 67.853461796997 | 2001 | 68.048397938606 | 2000 | 68.680259914855 | 1999 | 68.772126372395 | 1998 | 69.40622899395 | 1997 | 69.224736724177 | 1996 | 69.383822540892 | 1995 | 68.897602509523 | 1994 | 69.37934125028 | 1993 | 68.812457987901 | 1992 | 68.599596683845 | 1991 | 68.014788259019 | 1990 | 67.987900515348 | 1989 | 67.362760475017 | 1988 | 66.645753977145 | 1987 | 66.470983643289 | 1986 | 66.092314586601 | 1985 | 65.870490701322 | 1984 | 65.83912166704 | 1983 | 65.590410038091 | 1982 | 65.37530808873 | 1981 | 65.180371947121 | 1980 | 64.821868698185 | 1979 | 62.74703114497 | 1978 | 62.554335648667 | 1977 | 61.617745910822 | 1976 | 60.833520053776 | 1975 | 60.311449697513 | 1974 | 59.668384494734 | 1973 | 59.209052207036 | 1972 | 58.632432674643 | 1971 | 58.10144732715 | 1970 | 57.590625980195 | 1969 | 56.972263297038 | 1968 | 56.544338396738 | 1967 | 55.872205045481 | 1966 | 55.424116144643 | 1965 | 54.711654792311 | 1964 | 54.017116996012 | 1963 | 53.434601424923 | 1962 | 52.829681408792 | 1961 | 52.359188062912 |
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