Year % 2000 24.042319985930085 2001 23.67910064311802 2002 23.62095981761742 2003 23.521311456689325 2004 23.228208629386767 2005 22.62848754792298 2006 21.619270696558722 2007 20.94745346937819 2008 20.625557121890385 2009 20.253884546029973 2010 19.92141672883771 2011 19.50269988896313 2012 19.04519165446458 2013 18.511002876490736 2014 18.230238389311705 2015 17.81580874014912 2016 17.69811194570159 2017 17.298163479424918 2018 17.021675057069096 2019 16.818579016114068