Year Number 1998 1.672470370041864 1999 1.2720760965037876 2000 0.7542268434045184 2001 0.9016221068865042 2002 1.1845862947276076 2003 1.2783920797136883 2004 1.2754542449700392 2005 1.7683517895782945 2006 2.2510267111721114 2007 9.297079198129573 2008 4.761734871380245 2009 3.5595737810926957 2010 2.525657978643838 2011 2.4798392016122928 2012 2.373702538341065 2013 2.6952770919871636 2014 3.591938096632143 2015 3.5482690016668204 2016 2.9271099706617254 2017 1.6311668148842065 2018 1.6122010050208513 2019 1.5853781421436675 2020 1.1363091356556305 2021 1.0050177820909365 2022 0.6185816593372784