Year Percent 1990 0.77329 1991 1.22887 1992 1.59169 1993 1.76818 1994 1.58009 1995 1.294 1996 1.3056 1997 1.14377 1998 0.93384 1999 0.75742 2000 0.6207 2001 0.56667 2002 0.67444 2003 0.66498 2004 0.61466 2005 0.55375 2006 0.48291 2007 0.43077 2008 0.43735 2009 0.72651 2010 0.92024 2011 0.86202 2012 0.75787 2013 0.76808 2014 0.74297 2015 0.69853 2016 0.72845 2017 0.67276