| Year | Value | | 2022 | 43.320634720735 | | 2021 | 42.974159909206 | | 2020 | 42.723428922154 | | 2019 | 43.032002188184 | | 2018 | 42.566779778996 | | 2017 | 42.160945613071 | | 2016 | 41.595806009945 | | 2015 | 41.039699275695 | | 2014 | 40.613735268299 | | 2013 | 40.009521089213 | | 2012 | 39.522151286516 | | 2011 | 39.099389382819 | | 2010 | 38.670021273114 | | 2009 | 38.274317586411 | | 2008 | 37.644846074023 | | 2007 | 37.10883596706 | | 2006 | 36.673548979124 | | 2005 | 36.261726078799 | | 2004 | 35.943760646849 | | 2003 | 35.641165125365 | | 2002 | 35.445488333678 | | 2001 | 35.349486695456 | | 2000 | 34.990245805697 | | 1999 | 34.824391409382 | | 1998 | 34.696977917639 | | 1997 | 34.61836712086 | | 1996 | 34.671069342139 | | 1995 | 34.677001094912 | | 1994 | 34.690275898582 | | 1993 | 34.698411745279 | | 1992 | 34.730538922156 | | 1991 | 34.737269349652 |
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