Year | Value | 2021 | 23.076923076923 | 2020 | 23.076923076923 | 2019 | 23.076923076923 | 2018 | 23.076923076923 | 2017 | 23.076923076923 | 2016 | 23.076923076923 | 2015 | 23.076923076923 | 2014 | 23.076923076923 | 2013 | 23.076923076923 | 2012 | 23.076923076923 | 2011 | 23.076923076923 | 2010 | 21.923076923077 | 2009 | 21.153846153846 | 2008 | 19.615384615385 | 2007 | 19.576923076923 | 2006 | 19.269230769231 | 2005 | 19.230769230769 | 2004 | 30.884615384615 | 2003 | 31.153846153846 | 2002 | 31.153846153846 | 2001 | 35.769230769231 | 2000 | 36.538461538461 | 1999 | 38.461538461539 | 1998 | 34.615384615385 | 1997 | 34.615384615385 | 1996 | 34.615384615385 | 1995 | 38.461538461539 | 1994 | 38.461538461539 | 1993 | 46.153846153846 | 1992 | 46.153846153846 | 1991 | 46.153846153846 | 1990 | 46.153846153846 | 1989 | 46.153846153846 | 1988 | 46.153846153846 | 1987 | 46.153846153846 | 1986 | 46.153846153846 | 1985 | 50 | 1984 | 50 | 1983 | 53.846153846154 | 1982 | 53.846153846154 | 1981 | 57.692307692308 | 1980 | 57.692307692308 | 1979 | 42.857142857143 | 1978 | 42.857142857143 | 1977 | 42.857142857143 | 1976 | 42.857142857143 | 1975 | 42.857142857143 | 1974 | 42.857142857143 | 1973 | 42.857142857143 | 1972 | 42.857142857143 | 1971 | 42.857142857143 | 1970 | 42.857142857143 | 1969 | 51.428571428571 | 1968 | 57.142857142857 | 1967 | 57.142857142857 | 1966 | 57.142857142857 | 1965 | 57.142857142857 | 1964 | 57.142857142857 | 1963 | 57.142857142857 | 1962 | 57.142857142857 | 1961 | 57.142857142857 |
|