Year Percent 1990 1.25077 1991 0.57793 1992 0.55677 1993 0.53977 1994 0.52331 1995 0.50461 1996 0.48685 1997 0.47046 1998 0.45513 1999 1.19403 2000 1.24997 2001 0.86463 2002 0.83369 2003 0.51671 2004 0.55806 2005 0.54087 2007 0.38225 2008 0.36982 2009 0.35758 2010 0.34534 2011 0.33316 2012 0.32129 2013 0.31004 2014 0.29942 2015 0.2893 2016 0.27947 2017 0.27004 2018 0.26127 2019 0.25305 2020 0.24723