Year Number 1996 30 1998 27.8606967926025 2000 25.3731346130371 2002 15.9203977584839 2003 23.3830852508545 2004 21.634614944458 2005 21.634614944458 2006 20.6730766296387 2007 25 2008 25.480770111084 2009 27.014217376709 2010 27.962085723877 2011 27.6995296478271 2012 24.8826293945313 2013 26.7605628967285 2014 30.5418720245361 2015 30.5418720245361 2016 34.4827575683594 2017 33.9901466369629 2018 30.5825233459473 2019 30.917875289917 2020 32.8502426147461 2021 31.8840579986572 2022 32.3671493530273