Year Percent 1992 0.34022 1993 0.23488 1994 0.07113 1995 0.15296 1996 0.23537 1997 0.78654 1998 0.46862 1999 1.12688 2000 1.224 2001 0.82877 2002 1.02363 2003 2.25956 2004 2.33192 2005 2.34022 2006 3.02982 2007 3.44703 2008 3.35146 2009 3.53991 2010 3.45044 2011 3.25837 2012 2.2089 2013 3.76586 2014 2.76606 2015 1.61393 2016 1.73689 2017 2.47534