Year | Value | 2022 | 8.6 | 2021 | 8.7 | 2019 | 6.6 | 2018 | 9 | 2017 | 9.7 | 2016 | 12 | 2015 | 11.5 | 2014 | 13.7 | 2013 | 14.2 | 2012 | 16.1 | 2011 | 18.4 | 2010 | 19.9 | 2009 | 20.7 | 2008 | 21.3 | 2007 | 16.8 | 2006 | 21 | 2005 | 24.2 | 2004 | 24.1 | 2003 | 28.4 | 2002 | 27.7 | 2001 | 27.5 | 2000 | 25.7 | 1999 | 30.4 | 1998 | 34.4 | 1996 | 30.8 | 1995 | 29.7 | 1991 | 39.2 | 1989 | 32.7 |
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