Year Percent 1999 58.32627 2000 67.2964 2001 45.38064 2002 37.66849 2003 39.17062 2004 43.9057 2005 43.07709 2006 52.84085 2007 48.68401 2008 21.83801 2009 30.01374 2010 25.17855 2011 18.95567 2012 23.24498 2013 28.88828 2014 27.29486