Year | Value | 2021 | 2.5016787689352 | 2020 | 2.4975341364633 | 2019 | 2.4939380492565 | 2018 | 2.4895231775324 | 2017 | 2.4877152802895 | 2016 | 2.4848174345798 | 2015 | 2.4820508093219 | 2014 | 2.480394364005 | 2013 | 2.4787376312497 | 2012 | 2.4770258220366 | 2011 | 2.4753691261178 | 2010 | 2.473712430199 | 2009 | 2.4509479147728 | 2008 | 2.4274806721171 | 2007 | 2.4047256355221 | 2006 | 2.3819733565492 | 2005 | 2.3592346814144 | 2004 | 2.3364794604125 | 2003 | 2.31371888216 | 2002 | 2.2909133217256 | 2001 | 2.2681586539352 | 2000 | 2.2454039861448 | 1999 | 2.2419934081353 | 1998 | 2.2385828301258 | 1997 | 2.2351722521163 | 1996 | 2.2317616741067 | 1995 | 2.2283510960972 | 1994 | 2.2249405065108 | 1993 | 2.2215299285013 | 1992 | 2.2181193504918 | 1991 | 2.2147087724823 | 1990 | 2.2112981944727 |
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