Year Number 1996 6.01092910766602 1998 3.82513666152954 2000 3.27868843078613 2002 10.2702703475952 2003 12.972972869873 2004 10.4477615356445 2005 14.2156858444214 2006 14.1463413238525 2007 15.0485439300537 2008 12.62135887146 2009 13.3971290588379 2010 11.0047845840454 2011 12.7962083816528 2012 8.05687236785889 2013 11.3744077682495 2014 6.73076915740967 2015 9.5238094329834 2016 7.14285707473755 2017 8.5714282989502 2018 8.09523773193359 2019 7.61904764175415 2020 6.1904764175415 2021 6.1904764175415 2022 6.13207530975342