Year | Value | 2021 | 19.1 | 2020 | 21.4 | 2019 | 18.5 | 2018 | 19.6 | 2017 | 20.1 | 2016 | 20.1 | 2015 | 20 | 2014 | 22 | 2013 | 25.3 | 2012 | 29.6 | 2011 | 33.3 | 2010 | 35.7 | 2009 | 34.3 | 2008 | 34.1 | 2007 | 37.8 | 2006 | 35.6 | 2005 | 35.2 | 2004 | 32.7 | 2003 | 35.9 | 2002 | 35.5 | 2001 | 52.4 | 2000 | 49.6 | 1999 | 47.1 | 1998 | 39.4 | 1997 | 40.7 | 1996 | 19.9 |
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