Year | Value | 2021 | 19.98582518083 | 2020 | 20.85210767376 | 2019 | 18.954259806668 | 2018 | 18.678118566674 | 2017 | 20.284411832667 | 2016 | 19.380992655872 | 2015 | 20.439294959269 | 2014 | 20.611242786827 | 2013 | 20.218157443689 | 2012 | 21.344495934969 | 2011 | 21.142007050185 | 2010 | 20.993566224333 | 2009 | 21.701637393959 | 2008 | 23.082653900009 | 2007 | 23.655829446943 | 2006 | 25.768353885967 | 2005 | 29.397178322255 | 2004 | 29.365369516645 | 2003 | 28.802889080802 | 2002 | 29.742984484904 | 2001 | 24.702773578215 | 2000 | 25.77790616123 | 1999 | 25.005654876613 | 1998 | 27.134187604048 | 1997 | 24.923764904958 | 1996 | 22.904435870884 | 1995 | 22.495208777114 | 1994 | 20.068025870093 | 1993 | 18.444548128233 | 1992 | 15.231639071679 | 1991 | 13.04436452321 | 1990 | 12.325321762863 |
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