Year Number 1996 0.840325474739075 1998 0.829069972038269 2000 0.72274261713028 2002 0.753255426883698 2003 0.743869483470917 2004 0.628187000751495 2005 0.556203484535217 2006 0.35609769821167 2007 0.191648334264755 2008 0.272778868675232 2009 0.417277067899704 2010 0.467300355434418 2011 0.403479129076004 2012 0.447511166334152 2013 0.53310090303421 2014 0.473634362220764 2015 0.491357654333115 2016 0.545390427112579 2017 0.492247939109802 2018 0.409032583236694 2019 0.451061338186264 2020 0.360985457897186 2021 0.326035767793655 2022 0.449057072401047