| Year | Value | | 2022 | 5.65 | | 2021 | 6.04 | | 2020 | 7.24 | | 2019 | 5 | | 2018 | 4.9 | | 2017 | 5 | | 2016 | 5 | | 2015 | 4.96 | | 2014 | 4.91 | | 2013 | 4.97 | | 2012 | 5.19 | | 2011 | 5.42 | | 2010 | 5.63 | | 2009 | 5.74 | | 2008 | 5.86 | | 2007 | 6.33 | | 2006 | 6.62 | | 2005 | 7.26 | | 2004 | 7.99 | | 2003 | 9.17 | | 2002 | 10.04 | | 2001 | 10.91 | | 2000 | 11.78 | | 1999 | 16.25 | | 1998 | 1.13 | | 1997 | 1.03 | | 1996 | 0.9 | | 1995 | 0.8 | | 1994 | 0.65 | | 1993 | 0.52 | | 1992 | 0.17 | | 1991 | 0.11 |
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