Year | Value | 2022 | 9.5 | 2021 | 10 | 2020 | 17.4 | 2019 | 9.6 | 2018 | 10.7 | 2017 | 12.4 | 2016 | 12.4 | 2015 | 12.8 | 2014 | 13.1 | 2013 | 14 | 2012 | 14.8 | 2011 | 16.3 | 2010 | 17.8 | 2009 | 20.5 | 2008 | 22.7 | 2007 | 26.5 | 2006 | 30.4 | 2005 | 35.2 | 2004 | 32.8 | 2003 | 32.3 | 2002 | 34.2 | 2001 | 37.5 | 2000 | 35.4 | 1999 | 36.3 | 1998 | 34.9 | 1997 | 35.9 |
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