Year Percent 1985 44.24729 1986 47.25984 1987 41.34462 1988 38.11325 1989 32.76359 1990 29.76504 1991 28.57143 1992 47.36842 1993 49.31973 2000 89.68583 2001 75.38894 2002 68.29095 2003 68.42474 2004 70.2503 2005 86.01863 2006 79.79625 2007 73.95818 2008 76.31842 2009 54.90769 2010 62.34599 2011 65.35271 2012 63.08923 2013 55.68875 2014 48.01637 2015 33.44838 2016 30.01704 2017 29.93561