Year | Value | 2021 | 19.151583512649 | 2020 | 17.47781553614 | 2019 | 17.336481840443 | 2018 | 17.35518263292 | 2017 | 16.854095786047 | 2016 | 16.320590544489 | 2015 | 15.70990024304 | 2014 | 15.715720542506 | 2013 | 15.747739745271 | 2012 | 16.099567257938 | 2011 | 16.780131317338 | 2010 | 16.620978716759 | 2009 | 16.05189409814 | 2008 | 18.267369130137 | 2007 | 18.086530785477 | 2006 | 17.155103975853 | 2005 | 16.473806951834 | 2004 | 15.689680856422 | 2003 | 16.721320376981 | 2002 | 16.840758716299 | 2001 | 16.05595561629 | 2000 | 16.960839457944 | 1999 | 18.064281796214 | 1998 | 20.152758263425 | 1997 | 20.90485320964 | 1996 | 21.655857762383 | 1995 | 22.369153190749 | 1994 | 22.782680730482 |
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