Year % 1999 9.64 2000 9.6 2001 10.02 2002 5.06 2003 4.95 2004 4.96 2005 4.18 2006 3.91 2007 3.34 2008 3.46 2009 3.24 2010 4.32 2011 3.14 2012 3.14 2013 3.88 2014 3.1 2015 2.88 2016 2.69 2017 3.58 2018 1.66 2019 2.73 2020 2.73 2021 2.85