Year % 1996 20.78 1997 15.07 1998 15.11 1999 17.4 2000 14.62 2001 12.5 2002 13.02 2003 13.17 2006 10.9 2007 10.59 2010 12.16 2011 9.32 2012 10 2013 9.73 2015 11.66 2016 9.17 2017 8.86 2020 8.66