Year Number 1996 16.0804023742676 1998 9.5 2000 7.96019887924194 2002 13.9303483963013 2003 14.4278602600098 2004 16.3461532592773 2005 14.8325357437134 2006 14.3540668487549 2007 16.7464122772217 2008 19.230770111084 2009 17.0616111755371 2010 14.2180099487305 2011 14.0845069885254 2012 15.4929580688477 2013 14.0845069885254 2014 12.0192308425903 2015 11.9047622680664 2016 12.8571424484253 2017 15.2380952835083 2018 16.6666660308838 2019 16.1904754638672 2020 18.5714282989502 2021 18.0952377319336 2022 12.2641506195068