Year % 2000 0.9193000918135307 2001 0.8870887372976455 2002 0.8284802156164947 2003 0.7869834511433842 2004 0.7612940133204903 2005 0.7275098493124263 2006 0.6793292399256242 2007 0.6658363744816611 2008 0.6551623082999429 2009 0.634256368224849 2010 0.6002982216016484 2011 0.5754719855586422 2012 0.5529024325326087 2013 0.5415423165376738 2014 0.5244369034404749 2015 0.5054149245466741 2016 0.49734163024752487 2017 0.48672630449257864 2018 0.48016798588912124 2019 0.47067119922013956 2020 0.4436717712233928