Year Number 1996 5.85106372833252 1998 1.06382977962494 2000 0 2002 1.05820107460022 2003 0 2004 1.45631062984467 2005 3.39805817604065 2006 5.79710149765015 2007 8.69565200805664 2008 9.61538505554199 2009 14.6919431686401 2010 12.3222751617432 2011 13.7440757751465 2012 18.0094795227051 2013 19.4312801361084 2014 20.9523811340332 2015 17.1428565979004 2016 21.4285717010498 2017 17.1428565979004 2018 15.5660381317139 2019 17.4528293609619 2020 18.3962268829346 2021 17.9245281219482 2022 16.9811325073242