Year | Value | 2021 | 2.46 | 2020 | 2.43 | 2019 | 2.24 | 2018 | 2.26 | 2017 | 2.3 | 2016 | 2.32 | 2015 | 2.35 | 2014 | 2.44 | 2013 | 2.45 | 2012 | 2.47 | 2011 | 2.51 | 2010 | 2.55 | 2009 | 2.55 | 2008 | 2.57 | 2007 | 2.47 | 2006 | 2.45 | 2005 | 2.5 | 2003 | 2.4 | 2002 | 2.56 | 2001 | 2.75 | 2000 | 2.78 | 1996 | 3.1099998951 | 1993 | 3.5 | 1990 | 3.3452999592 | 1987 | 3.5603001117706 | 1975 | 4.9951000213623 |
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