Year | Value | 2021 | 13.326287878788 | 2020 | 13.814859307359 | 2019 | 13.56367965368 | 2018 | 14.33408008658 | 2017 | 13.140692640693 | 2016 | 11.838744588745 | 2015 | 13.709956709957 | 2014 | 11.794372294372 | 2013 | 11.778138528139 | 2012 | 12.651515151515 | 2011 | 12.58658008658 | 2010 | 12.391774891775 | 2009 | 13.809523809524 | 2008 | 12.510822510822 | 2007 | 15.930735930736 | 2006 | 16.991341991342 | 2005 | 18.073593073593 | 2004 | 16.883116883117 | 2003 | 16.666666666667 | 2002 | 15.151515151515 | 2001 | 15.151515151515 | 2000 | 15.313852813853 | 1999 | 15.606060606061 | 1998 | 15.606060606061 | 1997 | 15.38961038961 | 1996 | 15.497835497835 | 1995 | 15.487012987013 | 1994 | 15.51948051948 | 1993 | 17.175324675325 | 1992 | 17.272727272727 | 1991 | 17.229437229437 | 1990 | 17.380952380952 | 1989 | 17.467532467533 | 1988 | 17.467532467533 | 1987 | 17.575757575758 | 1986 | 17.662337662338 | 1985 | 17.619047619048 | 1984 | 19.69696969697 | 1983 | 19.805194805195 | 1982 | 19.69696969697 | 1981 | 19.036796536797 | 1980 | 18.560606060606 | 1979 | 18.668831168831 | 1978 | 18.863636363636 | 1977 | 19.058441558442 | 1976 | 19.253246753247 | 1975 | 19.512987012987 | 1974 | 31.060606060606 | 1973 | 42.662337662338 | 1972 | 42.640692640693 | 1971 | 42.857142857143 | 1970 | 43.073593073593 | 1969 | 43.181818181818 | 1968 | 43.398268398268 | 1967 | 43.398268398268 | 1966 | 43.290043290043 | 1965 | 43.506493506493 | 1964 | 43.614718614719 | 1963 | 43.831168831169 | 1962 | 43.506493506493 | 1961 | 43.722943722944 |
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