Year | Value | 2021 | 3.0607392463434 | 2020 | 3.0535341162908 | 2019 | 3.0463289862382 | 2018 | 3.0391238561856 | 2017 | 3.0391238561856 | 2016 | 3.0391238561856 | 2015 | 3.0391238561856 | 2014 | 3.0222068508351 | 2013 | 2.9799942840812 | 2012 | 2.963132323521 | 2011 | 2.9462703629608 | 2010 | 2.9294084024007 | 2009 | 2.9294084024007 | 2008 | 2.9294084024007 | 2007 | 2.9294084024007 | 2006 | 2.9294084024007 | 2005 | 2.9294084024007 | 2004 | 2.9294084024007 | 2003 | 2.9294084024007 | 2002 | 2.9294084024007 | 2001 | 2.9294084024007 | 2000 | 2.9294084024007 | 1999 | 2.9279794226922 | 1998 | 2.9265504429837 | 1997 | 2.9251214632752 | 1996 | 2.9236924835667 | 1995 | 2.9222635038582 | 1994 | 2.9208345241498 | 1993 | 2.9194055444413 | 1992 | 2.9179765647328 |
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