Year | Value | 2021 | 26.114277801563 | 2020 | 25.230223847409 | 2019 | 26.453712194042 | 2018 | 26.644593907064 | 2017 | 24.518147052894 | 2016 | 23.767509674946 | 2015 | 23.321859372664 | 2014 | 24.745157113387 | 2013 | 24.552266956073 | 2012 | 24.427827154218 | 2011 | 23.987047854064 | 2010 | 23.817840437812 | 2009 | 23.83910851581 | 2008 | 23.555710774018 | 2007 | 24.380345488909 | 2006 | 23.929841204306 | 2005 | 25.335555453842 | 2004 | 24.042573185433 | 2003 | 24.630096128509 | 2002 | 24.781702871534 | 2001 | 24.984894192766 | 2000 | 25.472596895497 | 1999 | 25.100328459176 | 1998 | 25.601176944394 | 1997 | 25.244152327397 | 1996 | 24.697387080027 | 1995 | 24.473227069156 | 1994 | 25.028312977552 | 1993 | 23.754366341264 | 1992 | 22.185822353543 | 1991 | 21.608056331721 | 1990 | 22.876278331035 | 1989 | 22.597580114543 | 1988 | 23.561068658308 | 1987 | 24.360278476047 | 1986 | 24.160788270443 | 1985 | 24.865524971436 | 1984 | 24.894181370133 | 1983 | 25.452284233907 | 1982 | 22.933764402962 | 1981 | 22.796171703903 | 1980 | 22.336086772382 | 1979 | 21.882178756466 | 1978 | 23.67386781977 | 1977 | 22.816754957503 | 1976 | 20.333889064736 | 1975 | 20.665171662262 | 1974 | 17.659103414991 | 1973 | 17.195617554349 | 1972 | 16.664884016334 |
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