Year Number 1996 23.9361705780029 1998 18.6170215606689 2000 16.4021167755127 2002 16.9312171936035 2003 13.5678396224976 2004 16.019416809082 2005 12.62135887146 2006 15.4589376449585 2007 11.1111106872559 2008 10.0961542129517 2009 9.47867298126221 2010 12.7962083816528 2011 12.7962083816528 2012 10.4265403747559 2013 13.7440757751465 2014 9.0476188659668 2015 9.5238094329834 2016 10 2017 11.9047622680664 2018 12.2641506195068 2019 12.7358493804932 2020 14.6226415634155 2021 15.0943393707275 2022 15.0943393707275