Year Number 1996 19.1489353179932 1998 29.7872333526611 2000 14.2857141494751 2002 15.8730154037476 2003 20.1005020141602 2004 16.019416809082 2005 19.4174766540527 2006 13.5265703201294 2007 16.9082126617432 2008 15.384614944458 2009 14.6919431686401 2010 19.4312801361084 2011 19.9052124023438 2012 19.4312801361084 2013 19.4312801361084 2014 29.0476188659668 2015 28.5714282989502 2016 31.4285717010498 2017 30 2018 25.943395614624 2019 22.6415100097656 2020 25.943395614624 2021 27.8301887512207 2022 32.5471687316895