Year % 1992 5.13 1997 4.9 2001 5 2002 7.19 2003 4.92 2004 4.92 2005 4.92 2006 4.87 2007 4.72 2008 4.72 2009 4.72 2012 4.63 2013 4.63 2014 4.63 2015 4.72 2016 4.72 2017 4.73 2018 4.73 2019 4.74 2020 4.73 2021 4.73