| Year | Value | | 2021 | 71.299620296859 | | 2020 | 71.299620296859 | | 2019 | 71.299620296859 | | 2018 | 71.330686917501 | | 2017 | 71.619195580873 | | 2016 | 71.665314436638 | | 2015 | 71.653230678935 | | 2014 | 71.658409432236 | | 2013 | 71.680591037768 | | 2012 | 71.285300006905 | | 2011 | 71.257681419595 | | 2010 | 71.2335151557 | | 2009 | 71.249050611061 | | 2008 | 71.27666919837 | | 2007 | 71.230559439352 | | 2006 | 71.257939795637 | | 2005 | 71.289999654803 | | 2004 | 71.381226913384 | | 2003 | 71.3829530155 | | 2002 | 71.453723202265 | | 2001 | 71.433503063778 | | 2000 | 71.469750582549 | | 1999 | 71.550875981704 | | 1998 | 71.823595408648 | | 1997 | 72.243030982998 | | 1996 | 72.218865970484 | | 1995 | 72.241304910676 | | 1994 | 72.255113489255 | | 1993 | 72.305169586606 | | 1992 | 72.372486407181 |
|