Year % 1996 12.8 2001 14.1 2002 12 2003 11.7 2004 9.1 2005 16.4 2006 6.4 2007 6.4 2008 5.2 2009 5.8 2010 5.1 2011 4.9 2012 5.1 2013 4.3 2014 4.3 2015 3.7 2016 4.6 2017 4 2018 3.8 2019 3.6 2020 3.2 2021 3.1