Year % 1996 42.7 1997 24.93 1998 21.95 1999 24.9 2000 21.6 2001 19.8 2002 15.78 2003 15.46 2007 16.72 2010 14.24 2011 14.25 2012 14.36 2015 15.34 2016 12.01 2021 16.72