| Year | Value | | 2023 | -13.572125340343 | | 2022 | -7.1893397422677 | | 2021 | -3.7305161855397 | | 2020 | -11.049774962588 | | 2019 | -3.9458017480189 | | 2018 | 0.70965614694624 | | 2017 | 1.249305281332 | | 2016 | 2.7665626048126 | | 2015 | 8.698139448141 | | 2014 | 14.281472821863 | | 2013 | 15.804109841032 | | 2012 | 12.172739112831 | | 2011 | 10.750172712242 | | 2010 | 9.5073402656601 | | 2009 | 6.6359858508691 | | 2008 | 10.990323500675 | | 2007 | 10.767269519082 | | 2006 | 9.424874417757 | | 2005 | 11.709391905911 | | 2004 | 14.987124744783 | | 2003 | 12.650433956096 | | 2002 | 15.693065620937 | | 2001 | 21.066972335165 | | 2000 | 23.64120253081 | | 1999 | 25.482915856961 | | 1998 | 28.442663460269 | | 1997 | 31.0600679181 | | 1996 | 32.020563598992 | | 1995 | 29.918803769492 | | 1994 | 30.023152926372 | | 1993 | 30.851937438586 | | 1992 | 27.489249877003 | | 1991 | 27.826399258075 | | 1990 | 27.922390671327 |
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