Year % 1996 4.37 1997 4.37 1998 4.37 1999 4.37 2000 4.37 2001 4.2 2002 4.2 2003 4.16 2004 4.03 2005 3.98 2006 3.93 2007 3.77 2008 3.71 2010 3.3 2011 3.07 2012 4.37 2013 4.41 2015 1.86 2019 3.4 2021 2.89