Year % 2000 0.9697529688181686 2001 0.9394260823483923 2002 0.9053690551463168 2003 0.871886941753236 2004 0.8339035619531489 2005 0.7920451615646735 2006 0.7645453883457319 2007 0.7205936919141851 2008 0.7049455029983044 2009 0.6486283435034205 2010 0.6377124439488425 2011 0.6096313130472286 2012 0.5711319344106396 2013 0.5529769747893267 2014 0.5287630250094586 2015 0.524515759728388 2016 0.5012071788663969 2017 0.4843137038211993 2018 0.4698971872994593 2019 0.4584337873244363 2020 0.44709192804048986