Year | Value | 2021 | 17.392974330503 | 2020 | 16.127030379683 | 2019 | 17.083281079513 | 2018 | 17.574936317596 | 2017 | 17.161113590549 | 2016 | 16.951157821602 | 2015 | 16.818233122225 | 2014 | 16.235283708122 | 2013 | 15.668958004328 | 2012 | 16.416650417932 | 2011 | 16.999651001969 | 2010 | 16.865692803044 | 2009 | 17.129578266469 | 2008 | 18.523946106197 | 2007 | 19.074830221728 | 2006 | 18.08266168588 | 2005 | 18.425098651308 |
|