| Year | Value | | 2021 | 38.602329450915 | | 2020 | 39.163893510815 | | 2019 | 39.205490848586 | | 2018 | 39.288685524126 | | 2017 | 39.080698835274 | | 2016 | 39.226289517471 | | 2015 | 39.278732165883 | | 2014 | 39.297004991681 | | 2013 | 39.373648311429 | | 2012 | 40.080685410082 | | 2011 | 40.128514390285 | | 2010 | 40.437919777089 | | 2009 | 40.133083801206 | | 2008 | 40.27027027027 | | 2007 | 40.12474012474 | | 2006 | 40.31185031185 | | 2005 | 40.35343035343 | | 2004 | 40.2079002079 | | 2003 | 46.476823945126 | | 2002 | 46.507276507277 | | 2001 | 46.881496881497 | | 2000 | 50.727650727651 | | 1999 | 50.790020790021 | | 1998 | 50.790020790021 | | 1997 | 50.831600831601 | | 1996 | 50.810810810811 | | 1995 | 50.852390852391 | | 1994 | 50.852390852391 | | 1993 | 50.852390852391 |
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