Year Number 1996 3.82513666152954 1998 2.7322404384613 2000 3.27868843078613 2002 3.78378367424011 2003 5.40540552139282 2004 12.93532371521 2005 12.7450981140137 2006 18.536584854126 2007 8.73786449432373 2008 16.990291595459 2009 12.4401912689209 2010 11.9617223739624 2011 11.8483409881592 2012 23.6966819763184 2013 24.1706161499023 2014 17.3076915740967 2015 14.2857141494751 2016 21.4285717010498 2017 18.5714282989502 2018 13.3333330154419 2019 12.380952835083 2020 5.7142858505249 2021 6.1904764175415 2022 6.13207530975342