Year | Value | 2021 | 20.740724223315 | 2020 | 21.195673605404 | 2019 | 21.708274493613 | 2018 | 22.61705992291 | 2017 | 23.340040900483 | 2016 | 23.874396785295 | 2015 | 24.909851108733 | 2014 | 25.432607961617 | 2013 | 25.648080548166 | 2012 | 25.611085205123 | 2011 | 25.377910352961 | 2010 | 25.151069924964 | 2009 | 24.831574459667 | 2008 | 24.712810862485 | 2007 | 24.545448229628 | 2006 | 24.312789970846 | 2005 | 24.222143386328 | 2004 | 24.18515968264 | 2003 | 24.21765323514 | 2002 | 24.246547322233 | 2001 | 24.483513064114 | 2000 | 24.677662910806 | 1999 | 24.990943852538 | 1998 | 25.385858901407 | 1997 | 25.893139084814 | 1996 | 26.655103184056 | 1995 | 27.842930311714 | 1994 | 29.158298246564 | 1993 | 30.557380636023 | 1992 | 31.756680744985 | 1991 | 32.705258497268 | 1990 | 33.640560627968 | 1989 | 34.777660504416 | 1988 | 36.006597061214 | 1987 | 37.17109645712 | 1986 | 38.328271185328 | 1985 | 39.364896243628 | 1984 | 40.169508467731 | 1983 | 40.871763394317 | 1982 | 41.368697344101 | 1981 | 41.604983318139 | 1980 | 42.053746231213 | 1979 | 42.327563061806 | 1978 | 42.208989826697 | 1977 | 42.274755192616 | 1976 | 42.472598988232 | 1975 | 42.520814548035 | 1974 | 42.615201977663 | 1973 | 42.812948811946 | 1972 | 43.277126584443 | 1971 | 43.803704169724 | 1970 | 44.26592851865 | 1969 | 44.758913951971 | 1968 | 45.142356755948 | 1967 | 45.597003706137 | 1966 | 45.980013174431 | 1965 | 46.333842464088 | 1964 | 46.81611749163 | 1963 | 47.274199641512 | 1962 | 47.75163188975 | 1961 | 47.552571738537 | 1960 | 47.808689074049 |
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