Year % 1997 17.4545454545455 1998 17.4545454545455 1999 16.3636363636364 2001 22.2627737226277 2002 22.2627737226277 2003 21.3559322033898 2004 21.3559322033898 2005 30.4075235109718 2006 30.4075235109718 2007 30.4075235109718 2008 30.4075235109718 2009 30.6501547987616 2011 36 2012 36 2013 36 2014 36 2015 36 2016 36.5591397849462 2017 37.1794871794872 2018 37.1794871794872 2019 36.8956743002545 2020 36.71875 2021 36.8556701030928 2022 36.8556701030928 2023 37.4045801526718