Year Percent 1995 2.17 1996 3.36 1997 3.08 1998 3.75 1999 4.34 2001 4.29 2002 3.62 2003 4.02 2004 3.45 2005 3.41 2006 3.35 2007 3.05 2008 2.57 2009 3.2 2011 2.47 2012 2.69 2013 2.51 2014 2.52 2015 3.33 2016 5.12 2017 6.05 2018 6 2019 6.08 2020 7.36