Year Number 1996 56.5 1998 41.7910461425781 2000 51.7412948608398 2002 50.7462692260742 2003 55.7213935852051 2004 56.730770111084 2005 58.1730766296387 2006 51.4423065185547 2007 52.8846168518066 2008 51.9230766296387 2009 53.0805702209473 2010 51.6587677001953 2011 50.7042236328125 2012 48.8262901306152 2013 46.0093879699707 2014 43.8423652648926 2015 41.3793106079102 2016 34.4827575683594 2017 32.019702911377 2018 29.6116504669189 2019 28.9855079650879 2020 29.9516906738281 2021 29.9516906738281 2022 28.9855079650879