Year | Value | 2021 | 14.887047855686 | 2020 | 15.222366466295 | 2019 | 15.623433824198 | 2018 | 16.103546905572 | 2017 | 16.391775823285 | 2016 | 16.603294370533 | 2015 | 17.119936041391 | 2014 | 17.394638645408 | 2013 | 17.621500745824 | 2012 | 17.91159734721 | 2011 | 18.243557502564 | 2010 | 18.446183287237 | 2009 | 18.690249715661 | 2008 | 18.916495477261 | 2007 | 19.252939010221 | 2006 | 19.641791222636 | 2005 | 20.061248459279 | 2004 | 20.413269044186 | 2003 | 20.75172564534 | 2002 | 21.313197387645 | 2001 | 21.869200154695 | 2000 | 22.411411495647 | 1999 | 22.93670655856 | 1998 | 23.404734213585 | 1997 | 23.871219177337 | 1996 | 24.365026729626 | 1995 | 24.921456257385 | 1994 | 25.388463939411 | 1993 | 25.878243749269 | 1992 | 26.299663307932 | 1991 | 26.866318345585 | 1990 | 27.412080225849 | 1989 | 27.967780806616 | 1988 | 28.492816429749 | 1987 | 29.11655992718 | 1986 | 29.697832815188 | 1985 | 30.274795555992 | 1984 | 30.807847296986 | 1983 | 31.355344331276 | 1982 | 31.880516000184 | 1981 | 32.325535751107 | 1980 | 32.766267280017 | 1979 | 33.265912205951 | 1978 | 33.746385054086 | 1977 | 34.134301787394 | 1976 | 34.538632157423 | 1975 | 34.919608697446 | 1974 | 35.372257392685 | 1973 | 35.924146691194 | 1972 | 36.349321874746 | 1971 | 36.784383333971 | 1970 | 37.293726385014 | 1969 | 37.797966116787 | 1968 | 38.347069061452 | 1967 | 39.06292398215 | 1966 | 39.799680137737 | 1965 | 40.49227600877 | 1964 | 41.186761938767 | 1963 | 41.720831909663 | 1962 | 42.088211729397 | 1961 | 42.372443720293 | 1960 | 42.629746190094 |
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