Year % 1989 5.28 1990 5.2 1991 5.31 1992 5.25 1993 5.12 1995 4.59 1996 4.44 1997 4.34 1998 4.49 1999 3.88 2000 3.87 2001 3.82 2002 3.98 2003 3.53 2004 3.31 2005 3.23 2006 3.14 2007 3.01 2008 3.1 2009 3 2010 2.96 2011 3.03 2012 2.99 2013 2.87 2014 2.93 2015 2.8 2016 2.76 2017 3.36 2018 3.25 2019 8.7 2020 2.87 2021 2.79