Year % 1988 16.31 1991 18.77 1993 14.22 1996 13.17 1997 11.32 1998 13.09 1999 11.51 2000 10.25 2001 7.33 2002 3.45 2003 7.4 2004 23.01 2005 2.43 2006 4.63 2007 6.97 2008 6.71 2009 7.36 2010 7.08 2011 5.31 2012 5.37 2013 6.04 2014 2.24 2016 4.66 2020 4.29 2021 4.33