Year Percent 1990 0.21416 1991 0.4065 1992 0.91895 1993 1.76514 1994 2.25994 1995 1.93394 1996 2.55155 1997 2.75461 1998 2.482 1999 1.74742 2000 1.26753 2001 0.84853 2002 0.93868 2003 0.9912 2004 1.33414 2005 0.31077 2006 0.81875 2007 0.96769 2008 0.90366 2009 1.42969 2010 1.73274 2011 1.52522 2012 1.51736 2013 1.51888 2014 1.49637 2015 1.42478 2016 1.31397 2017 1.28163