| Year | Value | | 2022 | 14.608143949243 | | 2021 | 3.8398449150015 | | 2020 | 1.6724409685576 | | 2019 | 2.6645613342543 | | 2018 | 2.534454241866 | | 2017 | 2.0759355367385 | | 2016 | 0.054999541670474 | | 2015 | 0.46449900464491 | | 2014 | 0.05382131323998 | | 2013 | 1.4382978723404 | | 2012 | 3.3349226769344 | | 2011 | 4.1302756264508 | | 2010 | 1.8011702213713 | | 2009 | 2.7532022391482 | | 2008 | 6.3586638015237 | | 2007 | 4.8373292831399 | | 2006 | 3.93032603841 | | 2005 | 3.3171782444804 | | 2004 | 3.5929759424951 | | 2003 | 2.3486416958276 | | 2002 | 3.1271422298461 | | 2001 | 5.7482798165137 | | 2000 | 8.9117441865877 | | 1999 | 4.0191387559809 | | 1998 | 8.208333333333 | | 1997 | 8.8810484846589 | | 1996 | 19.794966919671 | | 1995 | 27.951388563304 | | 1994 | 35.924705392964 | | 1993 | 72.878791386633 | | 1992 | 150.61583195688 | | 1991 | 118.52757890598 |
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