| Year | Value | | 2022 | 2.752 | | 2021 | 2.768 | | 2020 | 2.736 | | 2019 | 2.709 | | 2018 | 2.74 | | 2017 | 2.623 | | 2016 | 2.552 | | 2015 | 2.35 | | 2014 | 2.16 | | 2013 | 2.127 | | 2012 | 2.016 | | 2011 | 1.993 | | 2010 | 2.022 | | 2009 | 2.075 | | 2008 | 2.078 | | 2007 | 1.951 | | 2006 | 1.946 | | 2005 | 1.901 | | 2004 | 1.883 | | 2003 | 1.801 | | 2002 | 1.843 | | 2001 | 1.853 | | 2000 | 1.825 | | 1999 | 1.802 |
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