Year Percent 1992 0.35826 1993 0.55039 1994 0.79454 1995 0.56595 1996 0.60418 1997 0.63789 1998 0.62816 1999 0.53814 2000 0.36849 2001 0.34737 2002 0.53411 2003 0.66175 2004 1.00984 2005 1.01597 2006 1.04468 2007 0.89469 2008 1.08986 2009 1.15064 2010 0.8971 2011 1.17589 2012 1.2166 2013 1.32598 2014 1.29891 2015 1.61058 2016 1.67849 2017 1.356