Year | Value | 2020 | 25.709465695729 | 2019 | 27.45394174508 | 2018 | 26.78106656995 | 2017 | 26.22100376079 | 2016 | 26.02668424665 | 2015 | 24.815309256369 | 2014 | 24.053230430578 | 2013 | 24.009292197311 | 2012 | 24.332893031301 | 2011 | 23.364368298024 | 2010 | 24.278171726553 | 2009 | 24.955970204737 | 2008 | 24.684756616975 | 2007 | 24.786546428363 | 2006 | 24.014389942576 | 2005 | 23.215972844992 | 2004 | 24.167497305918 | 2003 | 24.071100071624 | 2002 | 21.859010192432 | 2001 | 21.414813015372 | 2000 | 22.494662535332 | 1999 | 21.892234514133 | 1998 | 20.851857286619 | 1997 | 19.914094207738 | 1996 | 20.109199571953 | 1995 | 21.744040012563 | 1994 | 21.103167553971 | 1993 | 21.328713503282 | 1992 | 23.468068202923 | 1991 | 23.082864476717 | 1990 | 23.486485028099 | 1989 | 24.494096800088 | 1988 | 23.478133621728 |
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