| Year | Value | | 2022 | 68.523906587325 | | 2021 | 68.030238740572 | | 2020 | 67.521875525505 | | 2019 | 67.793290830877 | | 2018 | 66.722751125917 | | 2017 | 65.677684947017 | | 2016 | 64.581913795785 | | 2015 | 60.948517310889 | | 2014 | 56.836784961828 | | 2013 | 55.741925971232 | | 2012 | 54.208906856525 | | 2011 | 52.913013626281 | | 2010 | 54.540101665433 | | 2009 | 55.854692107258 | | 2008 | 57.420399046461 | | 2007 | 59.117803076672 | | 2006 | 60.304169257994 | | 2005 | 61.619209955198 | | 2004 | 61.436358959579 | | 2003 | 61.094742396924 | | 2002 | 61.025052956822 | | 2001 | 60.734007168922 | | 2000 | 60.538582914804 | | 1999 | 60.826393872136 | | 1998 | 60.154434900927 | | 1997 | 59.855620940855 | | 1996 | 59.507155052541 | | 1995 | 59.171313037747 | | 1994 | 59.074388001379 | | 1993 | 58.768016037575 | | 1992 | 58.563723167754 | | 1991 | 58.403209232761 |
|