Year | Value | 2021 | 2.46 | 2020 | 2.29 | 2019 | 2.36 | 2018 | 2.41 | 2017 | 2.41 | 2016 | 2.39 | 2015 | 2.31 | 2014 | 2.25 | 2013 | 2.26 | 2012 | 2.37 | 2011 | 2.33 | 2010 | 2.16 | 2009 | 2.38 | 2008 | 2.33 | 2007 | 2.24 | 2006 | 2.11 | 2005 | 2.2 | 2004 | 2.01 | 2003 | 2.06 | 2002 | 2.04 | 2001 | 1.98 | 2000 | 2.08 | 1999 | 2.04 | 1998 | 2.04 | 1997 | 2.1 | 1992 | 2.696 | 1987 | 3 | 1982 | 3.5 | 1976 | 4.5 |
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