Year | Value | 2021 | 15.314510364546 | 2020 | 15.886347390994 | 2019 | 14.705882352941 | 2018 | 14.366378386105 | 2017 | 14.59867057394 | 2016 | 15.617182474448 | 2015 | 15.075762990494 | 2014 | 14.525409191623 | 2013 | 15.660067186048 | 2012 | 16.196126081052 | 2011 | 16.022800371668 | 2010 | 16.160388821385 | 2009 | 15.515331284397 | 2008 | 15.379529697663 | 2007 | 15.224072618112 | 2006 | 15.742262883282 | 2005 | 15.599313844614 | 2004 | 15.134729468944 | 2003 | 15.438496176113 | 2002 | 15.345542996137 | 2001 | 15.256116754901 | 2000 | 15.059379024181 | 1999 | 19.102128420676 | 1998 | 19.477732069397 | 1997 | 17.559842801 | 1996 | 17.61343336906 | 1995 | 19.978536934359 | 1994 | 19.746020389912 | 1993 | 18.99481309247 | 1992 | 21.677696297621 |
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