Year % 2001 12.24 2002 12.14 2003 11.7 2004 12.37 2005 12.7 2006 11.28 2007 12.12 2008 11.04 2009 12.37 2010 9.71 2011 11.18 2012 10.58 2013 10.84 2015 11.63 2017 11.84 2018 12.81