Year % 2002 16.46 2003 16.21 2004 16.23 2005 16.21 2006 15.81 2007 16.53 2008 16.7 2009 16.69 2012 10.32 2015 9.08 2016 8.98 2017 8.66 2020 9.95 2021 9.13