Year | Value | 2019 | 26.4 | 2018 | 27.2 | 2017 | 27.5 | 2016 | 28.3 | 2015 | 28.6 | 2014 | 28.8 | 2013 | 29.2 | 2012 | 32.8 | 2011 | 28.1 | 2010 | 27.8 | 2009 | 25.7 | 2008 | 28.9 | 2007 | 30.2 | 2006 | 35.1 | 2005 | 39.8 | 2004 | 42 | 2003 | 43.3 | 2002 | 38 | 2001 | 34 | 1999 | 41.5 | 1998 | 40.2 | 1997 | 38.1 | 1996 | 48.9 | 1995 | 46.1 | 1994 | 43.7 | 1993 | 43.4 | 1992 | 50 | 1991 | 54.4 | 1990 | 62.3 | 1989 | 60 |
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