Year % 2000 0.5299777457944602 2001 0.5051593122423842 2002 0.45573325273831666 2003 0.42342323605386617 2004 0.4071136591242347 2005 0.38134914301940737 2006 0.3376978142932119 2007 0.31990282515195984 2008 0.3051000049871261 2009 0.28584225528239643 2010 0.2540297618390551 2011 0.24391445312746304 2012 0.2267820292213366 2013 0.21482461917939438 2014 0.19346241437831216 2015 0.1858077393796263 2016 0.17695248775552655 2017 0.17098017468900426 2018 0.16256901978659394 2019 0.15662403928356994 2020 0.14923041464054654