Year % 1997 16.95 1999 16.89 2000 5.2 2001 5.2 2002 5.23 2003 4.39 2004 4.39 2005 4.39 2006 3.48 2007 3.3 2008 3.21 2009 3.25 2010 3.16 2012 2.73 2013 2.74 2018 2.17 2019 2.2 2020 2.2 2021 2.2