Year Percent 1992 2.50332 1993 2.03154 1994 1.94963 1995 2.51527 1996 2.29603 1997 2.6267 1998 2.47418 1999 2.03164 2000 1.94627 2001 1.92115 2002 1.91385 2003 1.87991 2004 1.97218 2005 1.96127 2006 1.94349 2007 1.95824 2008 1.94414 2009 1.96811 2010 1.88468 2011 1.79294 2012 1.79683 2013 1.66638 2014 1.70631 2015 1.98342 2016 1.93395 2017 1.94878 2018 1.95164 2019 1.97558 2020 1.99001