| Year | Value | | 2022 | 52.753423486907 | | 2021 | 52.422033878973 | | 2020 | 52.064006017855 | | 2019 | 52.391175397139 | | 2018 | 51.850983488792 | | 2017 | 51.267458853206 | | 2016 | 50.85406348729 | | 2015 | 50.27802964989 | | 2014 | 49.38557599638 | | 2013 | 48.645373463227 | | 2012 | 47.935374547021 | | 2011 | 47.025297756252 | | 2010 | 46.026542040194 | | 2009 | 45.114349690511 | | 2008 | 44.258082678046 | | 2007 | 43.287563192709 | | 2006 | 42.50855515944 | | 2005 | 41.599931778201 | | 2004 | 40.602360227778 | | 2003 | 39.366035099404 | | 2002 | 38.712180565803 | | 2001 | 38.0821062388 | | 2000 | 37.02991393957 | | 1999 | 36.441833954779 | | 1998 | 35.926932443021 | | 1997 | 35.567446252105 | | 1996 | 34.731381572046 | | 1995 | 33.952657612101 | | 1994 | 33.212221387261 | | 1993 | 32.524207167857 | | 1992 | 31.811120827516 | | 1991 | 31.343656143654 |
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