Year Number 1996 41.5 1998 41.2935333251953 2000 39.8009948730469 2002 39.8009948730469 2003 38.3084564208984 2004 39.9038467407227 2005 33.6538467407227 2006 30.769229888916 2007 32.211540222168 2008 30.2884616851807 2009 31.7535552978516 2010 30.3317527770996 2011 30.046947479248 2012 27.6995296478271 2013 28.1690139770508 2014 28.5714282989502 2015 28.0788173675537 2016 29.0640392303467 2017 30.5418720245361 2018 30.0970878601074 2019 28.5024147033691 2020 29.9516906738281 2021 29.9516906738281 2022 29.468599319458