Year % 2002 4 2003 4.82 2004 4.82 2005 4.19 2006 4.12 2007 3.88 2008 4.18 2009 3.19 2010 4.24 2011 4.24 2012 4.27 2013 4.09 2014 3.48 2015 3.28 2016 3.28 2017 3.26 2018 3.3 2019 3.3 2020 3.3 2021 3.19