Year | Value | 2022 | 50.000649662825 | 2021 | 49.49001468238 | 2020 | 49.065135194834 | 2019 | 49.005366214934 | 2018 | 49.117108220833 | 2017 | 49.327598976131 | 2016 | 49.800553512727 | 2015 | 50.090303132674 | 2014 | 50.094201109624 | 2013 | 49.923989449476 | 2012 | 49.903200239076 | 2011 | 49.695308135078 | 2010 | 50.689292257318 | 2009 | 50.55806036667 | 2008 | 50.832218078817 | 2007 | 51.329859802762 | 2006 | 52.61359354495 | 2005 | 53.562101269441 | 2004 | 53.545210035991 | 2003 | 52.809791718098 | 2002 | 53.527019476892 | 2001 | 53.230773228694 | 2000 | 52.59540298585 | 1999 | 52.365422345803 | 1998 | 51.867780621857 | 1997 | 50.988137156816 | 1996 | 51.146654886114 | 1995 | 51.314267894962 | 1994 | 52.166625521354 | 1993 | 51.859984667957 | 1992 | 51.848290737107 | 1991 | 52.060080818055 | 1990 | 51.55334381456 | 1989 | 51.839195457558 | 1988 | 51.015422995465 | 1987 | 51.228512402063 | 1986 | 50.001948988475 | 1985 | 49.543287034029 | 1984 | 48.871535672986 | 1983 | 47.708639216247 | 1982 | 48.323220248691 | 1981 | 50.170861322973 | 1980 | 50.126684250874 | 1979 | 50.53337317932 | 1978 | 49.43284435378 | 1977 | 49.412055143381 | 1976 | 49.248340111482 | 1975 | 49.325000324831 | 1974 | 49.800553512727 |
|