Year Percent 1999 11.24295 2000 13.72562 2001 15.77867 2002 13.64919 2003 13.31403 2004 13.23403 2005 16.62291 2006 16.56822 2007 16.55132 2008 15.81809 2009 12.95636 2010 13.04836 2011 13.91519 2012 13.74247 2013 12.90728 2014 13.22697 2015 10.60383 2016 9.12636