| Year | Value | | 2020 | 0.95339096234681 | | 2019 | 0.93418027095022 | | 2018 | 0.94486276845732 | | 2017 | 0.94910687134284 | | 2016 | 0.95467941142954 | | 2015 | 0.9577298587897 | | 2014 | 0.97095138522677 | | 2013 | 0.98285388798075 | | 2012 | 1.0061622425822 | | 2011 | 1.0188650873503 | | 2010 | 1.0355144355374 | | 2009 | 1.002733065449 | | 2008 | 1.0304966210953 | | 2007 | 1.0601935716416 | | 2006 | 1.094959221396 | | 2005 | 1.1320729344049 | | 2003 | 1.2558461555865 | | 2002 | 1.2741375201427 | | 2001 | 1.2937661139002 | | 2000 | 1.3368081501213 | | 1999 | 1.3477858155368 | | 1998 | 1.3807673287683 | | 1997 | 1.4973514353175 | | 1996 | 1.685820332099 | | 1995 | 1.7272148017088 | | 1994 | 1.9904234472337 | | 1993 | 2.4954287356219 | | 1992 | 2.5563805707918 | | 1991 | 3.1774063919273 |
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