Year % 2000 0.639340389558853 2001 0.63912449431268 2002 0.522867666475128 2003 0.545021160473383 2004 0.520400297432495 2005 0.520809182853934 2006 0.538600923249846 2007 0.511419778085891 2008 0.404729746255075 2009 0.391342436605612 2010 0.400506023472862 2011 0.384806647873362 2012 0.368825593696639 2013 0.360062541892997 2014 0.355674954936018 2015 0.348867211013635 2016 0.344759927821957 2017 0.335727593004869 2018 0.320603944629125 2019 0.299142168814467 2020 0.305263494620131