Year | Value | 2022 | 21.986937780276 | 2021 | 19.342499453891 | 2020 | 15.062673852635 | 2019 | 15.141670148606 | 2018 | 16.077946011917 | 2017 | 16.223398766695 | 2016 | 19.146283389947 | 2015 | 22.64210688422 | 2014 | 23.556760019545 | 2013 | 22.633352041677 | 2012 | 17.638991942691 | 2011 | 3.8509638542162 | 2010 | 7.8574610291946 | 2009 | 9.4279941752405 | 2008 | 13.954834432995 | 2007 | 21.650147375387 | 2006 | 19.513236439683 | 2005 | 23.162389520366 | 2004 | 18.701230059993 | 2003 | 21.468706795699 | 2002 | 23.000460667123 | 2001 | 26.857589652654 | 2000 | 21.223259881835 | 1999 | 13.012550296806 | 1998 | 13.510359708188 | 1997 | 17.236237520887 | 1996 | 13.966300652126 | 1995 | 15.504889734796 | 1994 | 18.100710852209 | 1993 | 13.980151343507 | 1992 | 17.371049370925 | 1991 | 19.727273202826 | 1990 | 19.664958246183 | 1974 | 50.092260548638 |
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