Year % 1996 7.82 1997 14.55 1998 7.82 1999 7.82 2000 18.06 2001 7.93 2002 7.97 2003 7.97 2004 7.94 2005 7.91 2006 7.92 2007 6.21 2008 7.84 2010 6.22 2011 6.18 2012 6.15 2013 6.14 2015 6.14 2016 6.14 2017 6.15 2018 6.15 2020 6.15 2021 6.15