Year Number 1996 15.0537633895874 1998 21.3903751373291 2000 20.2127666473389 2002 20.6349201202393 2003 25.3968257904053 2004 23.645320892334 2005 21.463415145874 2006 19.0243911743164 2007 16.5048542022705 2008 12.1359224319458 2009 11.0047845840454 2010 13.3333330154419 2011 15.6398105621338 2012 15.1658763885498 2013 15.6398105621338 2014 17.3076915740967 2015 15.7142858505249 2016 21.4285717010498 2017 16.6666660308838 2018 19.5238094329834 2019 23.8095245361328 2020 19.0476188659668 2021 19.5238094329834 2022 19.3396224975586