| Year | Value | | 2022 | 56.07157963465 | | 2021 | 53.813115528697 | | 2020 | 58.865434903003 | | 2019 | 63.439195525936 | | 2018 | 59.419157694141 | | 2017 | 60.897659630903 | | 2016 | 62.353292716004 | | 2015 | 60.321818571371 | | 2014 | 59.272496623498 | | 2013 | 56.477522958515 | | 2012 | 52.755667775462 | | 2011 | 56.993134882415 | | 2010 | 53.034174082501 | | 2009 | 52.67005824327 | | 2008 | 52.361778923415 | | 2007 | 51.984315152566 | | 2006 | 51.640375827856 | | 2005 | 49.790984193739 | | 2004 | 47.958569313862 | | 2003 | 47.356992268419 | | 2002 | 48.325430254553 | | 2001 | 49.23076036753 | | 2000 | 50.135521840339 | | 1999 | 50.746996748028 | | 1998 | 51.249999673776 | | 1997 | 51.164195114045 | | 1996 | 51.203181429706 | | 1995 | 51.258062756172 | | 1994 | 51.245781467499 | | 1993 | 51.290205312187 | | 1992 | 51.343338009645 | | 1991 | 51.370607496526 |
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