Year % 2000 21.86143839261328 2001 21.69918266434868 2002 21.561348853866352 2003 20.928000000832835 2004 19.966433778230037 2005 20.018023563051994 2006 20.123306595050863 2007 20.197513180594605 2008 19.979002236604355 2009 19.63312122836496 2010 19.93886563406247 2011 20.143513823189938 2012 20.25370198183883 2013 19.93317268199391 2014 19.64609957294815 2015 20.240631933148023 2016 20.153467793901772 2017 19.833152881664333 2018 19.662628117551943 2019 19.56337292440792