Year % 1997 10.989910008181079 1998 10.4504048582996 2000 12.26247783126425 2001 12.577890606969767 2002 13.677961909473163 2003 12.83407572383073 2004 14.404713531084928 2005 16.585804132973948 2006 16.950978631711266 2007 17.138707334785774 2008 17.193173565722592 2009 16.76086188625927 2010 17.760219855719683 2011 19.377162629757787 2012 19.709340300457217 2013 20.227774944756078 2014 19.419970631424377 2015 21.59918685414196 2016 21.860149355057704 2017 22.057161311157763 2018 21.895973154362423 2019 21.968002752451415 2020 22.60286067455414 2021 24.07145383799082 2022 24.076755973931945 2023 24.351558126516153