Year % 2001 2.38 2003 2.31 2004 2.31 2005 2.31 2006 2.26 2007 2.24 2008 2.23 2009 2.29 2010 2.29 2011 2.38 2012 2.95 2013 2.95 2014 2.97 2015 6.59 2016 5.7 2017 5.45 2018 5.83 2019 7.23 2020 5.85 2021 6.43