Year % 1998 6.191744340878831 2002 10.324947589098535 2003 10.575139146567716 2004 11.456790123456793 2005 12.049382716049386 2006 12.268993839835737 2007 12.909942738157218 2008 13.370055082623926 2009 13.674372848007868 2010 13.562653562653562 2011 13.8847858197932 2012 14.166666666666663 2013 18.301544050862866 2014 18.302976454908933 2015 17.981489643014537 2016 18.06963420008814 2017 18.52992957746479 2018 18.607705779334502 2019 18.432574430823124 2020 20.549738219895296 2021 20.454545454545453 2022 20.92616863259065 2023 21.04569420035149