Year Percent 1990 2.91943 1991 3.66482 1992 3.14617 1993 3.05157 1994 2.83971 1995 2.99484 1996 2.93324 1997 2.84443 1998 2.7623 1999 2.67408 2000 3.06521 2001 2.96184 2002 2.81955 2003 2.70508 2004 2.60088 2005 2.52372 2006 2.66965 2007 2.51894 2008 2.39962 2009 2.39628 2010 2.2554 2011 2.14394 2012 2.04493 2013 1.99037 2014 1.9379 2015 1.87107 2016 1.8006 2017 1.80949 2018 1.7351 2019 1.62732 2020 1.76304