Year % 2001 2.82 2003 3.34 2004 3.51 2005 3.48 2006 3.38 2007 3.6 2008 3.49 2009 3.88 2010 3.9 2011 3.96 2012 4.57 2013 4.5 2014 4.48 2015 6.26 2016 4.85 2017 4.51 2019 4.99 2020 4.73 2021 5.57