Year Number 1996 23.6180896759033 1998 24.5 2000 27.3631839752197 2002 30.348258972168 2003 28.8557205200195 2004 31.25 2005 32.5358848571777 2006 31.5789470672607 2007 33.4928245544434 2008 33.1730766296387 2009 33.1753540039063 2010 36.9668235778809 2011 32.8638496398926 2012 33.3333320617676 2013 23.474178314209 2014 22.115385055542 2015 20.9523811340332 2016 12.8571424484253 2017 15.2380952835083 2018 14.2857141494751 2019 14.2857141494751 2020 14.7619047164917 2021 15.7142858505249 2022 16.5094337463379