| Year | Value | | 2022 | 6.7252027153005 | | 2021 | 2.0414716313955 | | 2020 | 1.6208866171701 | | 2019 | 1.4110907895425 | | 2018 | 2.0280596307114 | | 2017 | 1.986661331712 | | 2016 | 1.2754316836741 | | 2015 | 1.8961740259236 | | 2014 | 1.6258650440261 | | 2013 | 1.9376208020523 | | 2012 | 2.031592683953 | | 2011 | 3.4291232472216 | | 2010 | 3.6260469557982 | | 2009 | 2.2669220945083 | | 2008 | 3.3208709038926 | | 2007 | 2.9326824816232 | | 2006 | 2.3707283190428 | | 2005 | 2.366581956798 | | 2004 | 2.280019169381 | | 2003 | 0.48400261181847 | | 2002 | 7.7705258343155 | | 2001 | 3.1075882703143 | | 2000 | 0.050018136346831 | | 1999 | 0.38943765356162 | | 1998 | 20.64285886706 | | 1997 | 33.180274375396 | | 1996 | 12.72547780871 | | 1995 | 7.7932185378922 | | 1994 | 22.56505269337 | | 1993 | 85.004751238716 | | 1992 | 226.00542125353 |
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