| Year | Value | | 2022 | 1.4309860997002 | | 2021 | 1.6054278480089 | | 2020 | 1.8054778310535 | | 2019 | 1.7765540159664 | | 2018 | 1.8971131573927 | | 2017 | 1.9697429690313 | | 2016 | 2.0816403154888 | | 2015 | 2.0029458903277 | | 2014 | 2.3579395937032 | | 2013 | 2.5705524351556 | | 2012 | 2.9837340982472 | | 2011 | 3.1029686854542 | | 2010 | 3.7096323905722 | | 2009 | 5.6065970514118 | | 2008 | 8.5201183953113 | | 2007 | 9.1591165170476 | | 2006 | 5.2183069509783 | | 2005 | 3.3391697967174 | | 2004 | 1.3738389718619 | | 2003 | 1.068489124722 | | 2002 | 1.000532997067 | | 2001 | 0.74018600525876 | | 2000 | 0.61558249075214 | | 1999 | 0.92437485593197 | | 1998 | 1.1369739561568 | | 1997 | 1.2535876689638 | | 1996 | 2.2101730270304 |
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