Year Percent 1979 1.62 1980 1.35 1981 1.5 1982 1.14 1983 1.52 1984 1.46 1985 1.6 1986 1.34 1987 1.09 1988 1.27 1989 1.54 1990 1.6 1991 1.77 1992 2.09 1993 1.98 1994 1.81 1995 1.47 1996 1.67 1997 1.6 1998 1.15 1999 0.92 2000 1.02 2001 1.44 2002 0.93 2003 0.88 2004 0.91 2005 1.01 2006 1.33 2007 1.17 2008 1.01 2009 1.27 2010 1.53 2011 1.15 2012 1.62 2013 1.51 2014 2.22 2015 1.51 2016 1.55 2017 1.4 2018 1.6 2019 1.86 2020 2.52