| Year | Value | | 2023 | 53.406513290374 | | 2022 | 52.89781426098 | | 2021 | 48.740050973113 | | 2020 | 48.812773176976 | | 2019 | 50.045956288027 | | 2018 | 48.098612503729 | | 2017 | 48.407894709521 | | 2016 | 48.650642645888 | | 2015 | 48.603404935541 | | 2014 | 48.295027436583 | | 2013 | 47.45708256644 | | 2012 | 46.532956648037 | | 2011 | 46.005326706547 | | 2010 | 46.250151678788 | | 2009 | 47.586277888806 | | 2008 | 49.562926621905 | | 2007 | 54.274725120141 | | 2006 | 50.153290182058 | | 2005 | 51.056699409834 | | 2004 | 49.620520323639 | | 2003 | 50.333489117129 | | 2002 | 49.948927157905 | | 2001 | 50.548822704736 | | 2000 | 50.854861604175 | | 1999 | 51.130899172075 | | 1998 | 51.593129196931 | | 1997 | 51.201527960655 | | 1996 | 51.175458457595 | | 1995 | 51.25752419873 | | 1994 | 50.809337869848 | | 1993 | 51.299384526503 | | 1992 | 51.214970983846 | | 1991 | 51.287358553333 |
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