Year % 1992 5.44 1997 4.92 2001 4.9 2002 6.53 2003 4.98 2004 4.88 2005 4.72 2006 4.9 2007 4.65 2008 4.47 2009 4.48 2012 4.36 2013 4.55 2014 4.55 2015 4.3 2016 4.25 2017 4.37 2018 4.37 2019 4.38 2020 4.38 2021 4.3