| Year | Value | | 2020 | 0.40667874954418 | | 2019 | 0.40339768422836 | | 2018 | 0.41952832737126 | | 2017 | 0.45872341206338 | | 2016 | 0.47323080625994 | | 2015 | 0.46353143418468 | | 2014 | 0.47643872198848 | | 2013 | 0.50450999385474 | | 2012 | 0.50835672867526 | | 2011 | 0.5121985876537 | | 2010 | 0.51988616691351 | | 2009 | 0.54303821913239 | | 2008 | 0.57242704775043 | | 2007 | 0.65290582994125 | | 2006 | 0.58909554687949 | | 2005 | 0.78240343381219 | | 2004 | 0.70298605041347 | | 2003 | 0.77772534214252 | | 2002 | 0.80447409024226 | | 2001 | 0.87398954376992 | | 2000 | 0.94500163727028 | | 1999 | 1.0354866050042 | | 1998 | 1.0755977755596 | | 1997 | 1.0861236600335 | | 1996 | 1.1554110998003 | | 1995 | 1.1638742559382 | | 1994 | 0.83772568139465 | | 1993 | 0.99379945585658 | | 1992 | 0.69164902961641 |
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