Year Number 1996 7.44680833816528 1998 10.638298034668 2000 14.8148145675659 2002 15.8730154037476 2003 21.608039855957 2004 20.3883495330811 2005 26.2135925292969 2006 26.0869560241699 2007 23.6714973449707 2008 15.865385055542 2009 19.9052124023438 2010 13.2701425552368 2011 15.6398105621338 2012 18.0094795227051 2013 18.4834117889404 2014 8.09523773193359 2015 9.0476188659668 2016 9.0476188659668 2017 8.5714282989502 2018 6.60377359390259 2019 4.24528312683105 2020 4.24528312683105 2021 6.13207530975342 2022 8.01886749267578