Year | Value | 2021 | 10.174763538687 | 2020 | 10.843012265456 | 2019 | 12.071394169478 | 2018 | 12.441414732908 | 2017 | 13.614650850306 | 2016 | 14.310070335703 | 2015 | 13.486121665602 | 2014 | 14.694632503406 | 2013 | 14.300295403803 | 2012 | 15.371988655573 | 2011 | 14.594962562201 | 2010 | 13.779955137236 | 2009 | 13.885160374883 | 2008 | 14.079863967645 | 2007 | 14.098034428846 | 2006 | 14.051022807738 | 2005 | 14.240578016103 | 2004 | 14.254692701446 | 2003 | 14.409257621894 | 2002 | 14.800292692578 | 2001 | 15.23956349984 | 2000 | 15.782875545401 | 1999 | 16.233460300814 | 1998 | 17.027770223218 | 1997 | 17.823410890562 | 1996 | 18.236910170017 | 1995 | 18.473550508188 | 1994 | 19.013249281161 | 1993 | 19.373064610171 | 1992 | 19.642658312059 | 1991 | 20.656986699373 | 1990 | 21.560379279117 | 1989 | 21.990845545914 | 1988 | 22.673406706937 | 1987 | 23.382466539596 | 1986 | 22.969615855199 | 1985 | 22.377634822783 | 1984 | 21.957143588162 | 1983 | 22.36622226981 | 1982 | 23.868021562906 | 1981 | 23.120740046922 | 1980 | 21.548581245287 | 1979 | 21.392277236471 | 1978 | 21.668934668846 | 1977 | 22.227818119642 | 1976 | 23.0369353696 | 1975 | 25.259688555677 | 1974 | 26.739650687673 | 1973 | 29.078345816483 | 1972 | 30.440275522934 | 1971 | 31.185264145396 | 1970 | 33.065131705988 | 1969 | 33.570318568211 | 1968 | 34.650765853044 | 1967 | 33.838465263511 | 1966 | 34.241871529498 | 1965 | 36.625991448385 | 1964 | 37.532700061077 | 1963 | 40.349649231506 | 1962 | 36.405164269733 | 1961 | 24.333748207761 | 1960 | 26.3005526159 |
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