Year | Value | 2021 | 23.77199043714 | 2020 | 23.233128001841 | 2019 | 24.262670476778 | 2018 | 24.865546895313 | 2017 | 25.053555002226 | 2016 | 25.229163540482 | 2015 | 24.338357668985 | 2014 | 25.993286191331 | 2013 | 25.738154768243 | 2012 | 25.691673128831 | 2011 | 25.808127849234 | 2010 | 25.310118816304 | 2009 | 26.014510938454 | 2008 | 25.805875947562 | 2007 | 62.502794579508 | 2006 | 60.027665831113 | 2005 | 58.819451826027 | 2004 | 55.024006088874 | 2003 | 54.069669442609 | 2002 | 53.727325182236 | 2001 | 51.424094120965 | 2000 | 48.585271838509 | 1999 | 47.277411358474 | 1998 | 43.270299258733 | 1997 | 47.514888209426 | 1996 | 45.22370209312 | 1995 | 50.795167688454 | 1994 | 42.314009539659 | 1993 | 45.262922912174 | 1992 | 44.172040034101 | 1991 | 43.050834372674 | 1990 | 42.434326835817 | 1989 | 17.897013702005 | 1988 | 17.598912184008 | 1987 | 16.552153446496 | 1986 | 17.180321609022 | 1985 | 17.676665548389 | 1984 | 16.841518792331 | 1983 | 17.862844176626 | 1982 | 18.510966464815 | 1981 | 19.234036012698 | 1980 | 19.694242422364 | 1978 | 19.158553175836 | 1977 | 18.354830919928 | 1976 | 17.732636580082 | 1975 | 18.874721892246 | 1974 | 20.665999699945 | 1973 | 22.014396294686 | 1972 | 21.171189073004 |
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