Year | Value | 2021 | 7.9633827730132 | 2020 | 7.7949454469413 | 2019 | 7.6389101404392 | 2018 | 7.8207273809201 | 2017 | 7.9912895442003 | 2016 | 8.190702816097 | 2015 | 8.4401825217159 | 2014 | 8.6682831601512 | 2013 | 8.881855508777 | 2012 | 9.1049920485238 | 2011 | 9.3021140895755 | 2010 | 9.6294166196577 | 2009 | 9.9239982584412 | 2008 | 10.337251424052 | 2007 | 10.69461033072 | 2006 | 11.095517438588 | 2005 | 11.581489607137 | 2004 | 11.965846068952 | 2003 | 12.315792273836 | 2002 | 12.923991345452 | 2001 | 13.268782434621 | 2000 | 13.626962981554 | 1999 | 14.246143022556 | 1998 | 15.34380109281 | 1997 | 14.948023181661 | 1996 | 15.31954079243 | 1995 | 15.485270889315 | 1994 | 16.902935913594 | 1993 | 16.231394365525 | 1992 | 16.959635207722 | 1991 | 16.88358298944 | 1990 | 16.750928301368 | 1989 | 16.835760396584 | 1988 | 18.606259173975 | 1987 | 17.844276661335 | 1986 | 18.433728053617 | 1985 | 19.185044057462 | 1984 | 19.547218740588 | 1983 | 19.387945528586 | 1982 | 18.149718672989 | 1981 | 18.27077381841 | 1980 | 18.462795182418 | 1979 | 18.717564834455 | 1978 | 19.037951083533 | 1977 | 19.188142425989 | 1976 | 19.445311287 | 1975 | 20.071085605634 | 1974 | 20.317060814684 | 1973 | 20.322655683722 | 1972 | 21.037274983837 | 1971 | 20.784215115 | 1970 | 21.203451372001 | 1969 | 21.476562521774 | 1968 | 21.701604678754 | 1967 | 21.999340809161 | 1966 | 22.632005797451 | 1965 | 22.441758121714 | 1964 | 22.489368527025 | 1963 | 23.00467868306 | 1962 | 23.122304326947 | 1961 | 23.382257791928 | 1960 | 23.663024030629 |
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