Year | Value | 2022 | 14.1 | 2021 | 14.5 | 2020 | 19.9 | 2019 | 13.7 | 2018 | 13.9 | 2017 | 12.9 | 2016 | 14.2 | 2015 | 14.8 | 2014 | 15.1 | 2013 | 15.6 | 2012 | 15.6 | 2011 | 16.4 | 2010 | 15.6 | 2009 | 19.4 | 2008 | 20 | 2007 | 20.3 | 2006 | 25.1 | 2005 | 25.4 | 2004 | 27.9 | 2003 | 26.5 | 2002 | 27.8 | 2001 | 28 | 2000 | 36.1 | 1999 | 36.1 | 1998 | 33.6 | 1997 | 38.1 | 1996 | 41.3 | 1995 | 37.1 | 1994 | 36.6 | 1993 | 40.9 | 1992 | 48 | 1991 | 51.4 | 1990 | 45.6 | 1989 | 47.4 | 1986 | 63.4 | 1981 | 71.1 |
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