Year % 1996 23.64 1999 22.78 2000 21.01 2001 20.34 2002 20.78 2003 21.45 2004 20.2 2006 17.12 2007 19.23 2010 15.77 2011 13.15 2012 8.69 2013 15.39 2020 15.57 2021 15.62