Year % 1996 2.7 2001 2.6 2002 3 2003 3.1 2004 3.4 2005 2.3 2006 3.7 2007 3.8 2008 4 2009 4 2010 4.1 2011 4.1 2012 4.1 2013 4.3 2014 4.3 2015 4.3 2016 4.2 2017 4.3 2018 4.3 2019 4.3 2020 4.3 2021 4.3