| Year | Value | | 2022 | 23.467221110936 | | 2021 | 25.232652569432 | | 2020 | 27.349227566117 | | 2019 | 26.579097364393 | | 2018 | 27.315994052208 | | 2017 | 26.474063686997 | | 2016 | 23.45568899646 | | 2015 | 23.089994686121 | | 2014 | 24.443401687304 | | 2013 | 21.916232702969 | | 2012 | 20.367606216634 | | 2011 | 21.567649939442 | | 2010 | 21.909869662934 | | 2009 | 22.386731129187 | | 2008 | 27.413623026393 | | 2007 | 28.725862626052 | | 2006 | 28.429598531557 | | 2005 | 26.549483448659 | | 2004 | 25.681338143445 | | 2003 | 25.281842472127 | | 2002 | 25.804469817015 | | 2001 | 26.170836907008 | | 2000 | 25.551452963599 | | 1999 | 25.230715199792 | | 1998 | 25.882471647565 | | 1997 | 25.564029596725 | | 1996 | 24.531028291507 | | 1995 | 24.168329701983 |
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