Year Percent 1990 2.76262 1991 2.68377 1992 2.52608 1993 2.42065 1994 2.33695 1995 3.28458 1996 3.56196 1997 3.54692 1998 3.49008 1999 3.27932 2000 3.26631 2001 3.69372 2002 3.7543 2003 3.60021 2004 3.50665 2005 3.34956 2006 3.47038 2007 3.32034 2008 3.26977 2009 3.17245 2010 2.90711 2011 2.87494 2012 2.82797 2013 2.76823 2014 2.72543 2015 2.73569 2016 2.70147 2017 2.74741 2018 2.79433 2019 2.81397 2020 2.8039