Year Percent 2000 100 2001 100 2002 100 2003 100 2004 100 2005 100 2006 100 2007 100 2008 100 2009 100 2010 99.9972 2011 99.87454 2012 99.75189 2013 99.62924 2014 99.50659 2015 99.38394 2016 99.26129 2017 99.13864 2018 99.01599 2019 98.89334 2020 98.77069 2021 98.64804 2022 98.52539