Year % 1996 40.61 1997 25.02 1998 20.95 1999 26.33 2000 22.15 2001 19.22 2002 18.17 2003 16.66 2007 18.68 2010 16.97 2011 11.92 2012 17.47 2015 13.29 2016 9.56 2021 18.44