Year % 2000 0.597296148296224 2001 0.587786304710724 2002 0.573920122454704 2003 0.603490441951804 2004 0.604186930257361 2005 0.550103876320346 2006 0.580427709274188 2007 0.606055947559299 2008 0.618605569519772 2009 0.597379915726591 2010 0.546649105245142 2011 0.529967800892096 2012 0.529186729036615 2013 0.523452783961836 2014 0.436253373454207 2015 0.452054726573942 2016 0.347933846814829 2017 0.320238613448782 2018 0.271918414505547 2019 0.27518788519005 2020 0.287091945804871