Year % 1997 8.86 2002 10.64 2003 10.11 2004 11.91 2005 11.41 2006 10.93 2007 10.87 2008 11.98 2009 9.42 2010 8.07 2011 11.18 2012 10.2 2013 11.45 2014 12.09 2015 13.65 2016 13.32