Year % 1988 4.12 1989 4.07 1990 3.61 1991 4.04 1992 4.24 1993 4.36 1994 4.3 1995 5.22 1996 5.59 1997 4.33 1998 4.17 1999 4.42 2000 4.49 2001 5.75 2002 5.52 2003 5.23 2004 4 2005 3.58 2006 2.82 2007 2.74 2008 2.49 2009 2.91 2010 2.2 2011 2.37 2012 2.27 2013 1.18 2014 2.29 2015 2.3 2016 2.55 2017 2.51 2018 2.45 2019 3.53 2020 2.22 2021 1.84