Year | Value | 2021 | 14.935255541572 | 2020 | 15.25842566123 | 2019 | 15.662463474774 | 2018 | 16.155570882621 | 2017 | 16.478051120613 | 2016 | 16.71970611386 | 2015 | 17.223689737546 | 2014 | 17.507913780332 | 2013 | 17.737186667637 | 2012 | 18.028274622569 | 2011 | 18.34959639558 | 2010 | 18.567970544117 | 2009 | 18.81495599856 | 2008 | 19.057089597932 | 2007 | 19.400291955142 | 2006 | 19.777688470568 | 2005 | 20.170644177943 | 2004 | 20.50582514333 | 2003 | 20.831520918193 | 2002 | 21.381039523682 | 2001 | 21.926203599747 | 2000 | 22.451218473682 | 1999 | 22.964836186478 | 1998 | 23.437012552135 | 1997 | 23.912960606207 | 1996 | 24.437145463259 | 1995 | 24.987950537658 | 1994 | 25.473320946284 | 1993 | 25.964355284538 | 1992 | 26.389218845095 | 1991 | 26.951025187072 | 1990 | 27.469682990808 | 1989 | 28.024967973355 | 1988 | 28.544318304647 | 1987 | 29.16651407452 | 1986 | 29.749698693774 | 1985 | 30.299667119887 | 1984 | 30.823658034168 | 1983 | 31.364232673109 | 1982 | 31.902646462604 | 1981 | 32.414831500011 | 1980 | 32.86082514277 | 1979 | 33.35232908802 | 1978 | 33.823489902448 | 1977 | 34.15714749806 | 1976 | 34.511432434822 | 1975 | 34.831595665217 | 1974 | 35.217770383083 | 1973 | 35.710292478076 | 1972 | 36.097057842414 | 1971 | 36.510415731367 | 1970 | 37.004750107542 | 1969 | 37.510995360716 | 1968 | 38.064419173585 | 1967 | 38.768778892774 | 1966 | 39.497144224275 | 1965 | 40.181841708349 | 1964 | 40.87006214466 | 1963 | 41.414756808648 | 1962 | 41.834908462846 | 1961 | 42.18190345585 | 1960 | 42.495290854631 |
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