Year | Value | 2021 | 34.133741929371 | 2020 | 34.247323196197 | 2019 | 34.140799640376 | 2018 | 34.034276084556 | 2017 | 33.714705417096 | 2016 | 31.797281412332 | 2015 | 30.78530763204 | 2014 | 30.518998742489 | 2013 | 30.343234875386 | 2012 | 30.060947452462 | 2011 | 30.044968919089 | 2010 | 29.496372606615 | 2009 | 29.480394073242 | 2008 | 29.091583094499 | 2007 | 28.915819227395 | 2006 | 28.367222914921 | 2005 | 27.765364824537 | 2004 | 27.642862735344 | 2003 | 27.230083956541 | 2002 | 26.604258066097 | 2001 | 25.925170397743 | 2000 | 25.12730896465 | 1999 | 25.32444233455 | 1998 | 24.220427584912 | 1997 | 24.027225003726 | 1996 | 23.718652881203 | 1995 | 23.724172954951 | 1994 | 23.168301528508 | 1993 | 23.193141860375 | 1992 | 22.826056956121 | 1991 | 22.921554231964 | 1990 | 24.886148478944 | 1989 | 24.528447700061 | 1988 | 24.363949502365 | 1987 | 24.004040693984 | 1986 | 22.793488521007 | 1985 | 21.903100625424 | 1984 | 20.452977251776 | 1983 | 20.921079505622 | 1982 | 20.948679874363 | 1981 | 20.948679874363 | 1980 | 20.976280243104 | 1979 | 20.976280243104 | 1978 | 21.001672582346 | 1977 | 21.001672582346 | 1976 | 21.001672582346 | 1975 | 21.117594131058 | 1974 | 21.14188245555 | 1973 | 21.14188245555 | 1972 | 21.169482824291 | 1971 | 21.169482824291 | 1970 | 21.197083193031 | 1969 | 21.197083193031 | 1968 | 21.224683561772 | 1967 | 21.224683561772 | 1966 | 21.224683561772 | 1965 | 21.252283930513 | 1964 | 21.279884299254 | 1963 | 21.279884299254 | 1962 | 21.307484667995 | 1961 | 21.307484667995 |
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