| Year | Value | | 2021 | 27.484876184145 | | 2020 | 28.315855077281 | | 2019 | 29.146833970417 | | 2018 | 29.977812863553 | | 2017 | 30.808791756689 | | 2016 | 31.639770649826 | | 2015 | 32.470749542962 | | 2014 | 32.937128136945 | | 2013 | 33.403506730929 | | 2012 | 33.869885324913 | | 2011 | 34.336263918896 | | 2010 | 34.80264251288 | | 2009 | 35.80909921888 | | 2008 | 36.815555924879 | | 2007 | 37.822012630879 | | 2006 | 38.828469336879 | | 2005 | 39.834926042879 | | 2004 | 40.841382748878 | | 2003 | 41.847839454878 | | 2002 | 42.854296160878 | | 2001 | 43.860752866877 | | 2000 | 44.867209572877 | | 1999 | 45.698188466013 | | 1998 | 46.529167359149 | | 1997 | 47.360146252285 | | 1996 | 48.191125145421 | | 1995 | 49.022104038557 | | 1994 | 49.853082931693 | | 1993 | 50.68406182483 | | 1992 | 51.515040717966 | | 1991 | 52.346019611102 | | 1990 | 53.176998504238 |
|