Year % 1998 14.173062769424892 1999 14.749068595222461 2000 14.758214168758869 2001 15.112376690735276 2002 15.68998109640832 2003 15.079784423544343 2004 15.786379225869686 2005 16.016387046429966 2006 16.040856031128406 2007 16.745506149479656 2008 17.07873716241917 2009 17.21615201900237 2010 17.25085259568018 2011 17.66031358557881 2012 18.28507587747881 2013 18.915147004093793 2014 19.10251524390245 2015 19.365322118141865 2016 19.88918609094385 2017 20.70172028379822 2018 21.47005617442636 2019 21.970049297739745 2020 22.194281456645246 2021 22.991508817766164 2022 23.33395557214858 2023 23.63738527814198