Year % 2001 2.33 2002 1.99 2003 2.04 2004 2.5 2005 2.19 2006 2.39 2007 2.29 2008 2.24 2009 2.31 2010 1.4 2011 1.86 2012 1.79 2013 1.94 2015 1.84 2017 2.34 2018 2.61