Year | Value | 2021 | 16.36 | 2020 | 14.445 | 2019 | 13.089 | 2018 | 13.339 | 2017 | 13.088 | 2016 | 13.54 | 2015 | 14.133 | 2014 | 14.166 | 2013 | 13.8 | 2012 | 13.443 | 2011 | 13.074 | 2010 | 12.582 | 2009 | 12.093 | 2008 | 12.033 | 2007 | 12.21 | 2006 | 12.417 | 2005 | 12.501 | 2004 | 12.529 | 2003 | 12.803 | 2002 | 13.042 | 2001 | 12.897 | 2000 | 12.993 | 1999 | 13.577 | 1998 | 13.399 | 1997 | 13.511 | 1996 | 14.484 | 1995 | 13.439 | 1994 | 13.533 | 1993 | 12.043 | 1992 | 11.454 | 1991 | 11.619 | 1990 | 10.588 | 1989 | 9.989 | 1988 | 10.258 | 1987 | 10.159 | 1986 | 10.321 | 1985 | 11.754 | 1984 | 11.6 | 1983 | 11.387 | 1982 | 10.783 | 1981 | 11.019 | 1980 | 11.189 | 1979 | 11.308 | 1978 | 11.369 | 1977 | 11.206 | 1976 | 11.032 | 1975 | 10.947 | 1974 | 10.858 | 1973 | 10.672 | 1972 | 10.585 | 1971 | 10.462 | 1970 | 10.197 | 1969 | 9.996 | 1968 | 9.88 | 1967 | 9.791 | 1966 | 9.755 | 1965 | 9.763 | 1964 | 9.867 | 1963 | 10.123 | 1962 | 10.393 | 1961 | 10.731 | 1960 | 11.003 |
|