Year % 1998 5.36 1999 4.84 2000 5.84 2001 8.77 2002 8.95 2003 12.2 2004 11.93 2005 12.1 2006 11.09 2007 13.45 2015 15.22 2016 15.57 2017 13.8 2018 15.66