Year Number 1996 35.5 1998 32.8358192443848 2000 32.3383102416992 2002 34.3283576965332 2003 39.3034820556641 2004 34.6153831481934 2005 24.0384616851807 2006 25 2007 21.1538467407227 2008 21.1538467407227 2009 20.8530807495117 2010 18.4834117889404 2011 13.6150236129761 2012 14.5539903640747 2013 13.6150236129761 2014 14.7783250808716 2015 16.2561569213867 2016 17.7339897155762 2017 15.2709360122681 2018 16.990291595459 2019 15.9420289993286 2020 15.4589376449585 2021 19.8067626953125 2022 18.8405799865723