Year | Value | 2022 | 4 | 2021 | 4.3 | 2020 | 5.2 | 2019 | 3.5 | 2018 | 4.2 | 2017 | 5.4 | 2016 | 8 | 2015 | 8.8 | 2014 | 10.9 | 2013 | 13.7 | 2012 | 14.3 | 2011 | 13.7 | 2010 | 16.7 | 2009 | 16.8 | 2008 | 18.6 | 2007 | 18.1 | 2006 | 18.6 | 2005 | 21.4 | 2004 | 27.9 | 2003 | 21.8 | 2002 | 17.7 | 2001 | 16.1 | 2000 | 16.1 | 1997 | 16.2 | 1996 | 17.6 | 1992 | 23.1 | 1989 | 37 | 1986 | 16.9 |
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