Year Percent 1995 22.3409 1996 19.2064 1997 10.78319 1998 9.9658 1999 11.48346 2000 13.11063 2001 10.10813 2002 9.20514 2003 8.97152 2004 8.24843 2005 8.72708 2006 12.31379 2007 13.74247 2008 14.12751 2009 21.35974 2010 24.18044 2011 21.09111 2012 19.72928 2013 18.59529 2014 18.37393 2015 20.43543 2016 20.0896 2017 22.16425