Year % 2002 4.01 2003 4.94 2004 4.93 2005 4.11 2006 4.09 2007 4.13 2008 4.04 2009 4.28 2010 4.66 2011 4.66 2012 4.29 2013 4.31 2014 4 2015 3.8 2016 3.8 2017 3.91 2018 3.96 2019 4.13 2020 4.11 2021 4.11