| Year | Value | | 2022 | 5.589 | | 2021 | 6.621 | | 2020 | 7.66 | | 2019 | 5.636 | | 2018 | 6.029 | | 2017 | 5.89 | | 2016 | 5.6 | | 2015 | 5.6 | | 2014 | 5.877 | | 2013 | 5.6 | | 2012 | 5.622 | | 2010 | 5.55 | | 2009 | 5.377 | | 2008 | 5.085 | | 2007 | 5.734 | | 2006 | 6.254 | | 2005 | 6.051 | | 2004 | 5.822 | | 2003 | 5.563 | | 2002 | 5.265 | | 2001 | 4.618 | | 2000 | 4.57 | | 1999 | 4.346 | | 1992 | 7.2 |
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