Year % 1997 27.6264591439689 1998 27.6264591439689 2000 26.4591439688716 2002 30.7392996108949 2003 30.7392996108949 2004 33.7254901960784 2005 36.1867704280156 2006 35.0194552529183 2007 40 2008 40 2009 38.5214007782101 2010 38.5214007782101 2011 37.3540856031128 2012 37.3540856031128 2013 36.5758754863813 2014 36.5758754863813 2016 35.7976653696498 2017 38.1322957198444 2018 38.9105058365759 2019 40.1574803149606 2020 40.8560311284047 2021 44.7470817120623 2022 44.7470817120623 2023 43.1906614785992