Year Percent 1990 3.45283 1991 3.23897 1992 2.20534 1993 2.15338 1994 2.56409 1995 7.6413 1996 7.48291 1997 6.90426 1998 6.75874 1999 6.62862 2000 6.4934 2001 6.35964 2002 6.22787 2003 6.09784 2004 5.96596 2005 5.82989 2006 5.68865 2007 5.54897 2008 5.41988 2009 5.30445 2010 5.19769 2011 5.09616 2012 5.00028 2013 4.90787 2014 4.81685 2015 4.72895 2016 4.64435 2017 4.55943 2018 4.48395 2019 4.4022 2020 4.35767