Year Percent 1991 24.618 1992 25.219 1993 25.887 1994 23.993 1995 24.808 1996 24.597 1997 28.292 1998 29.243 1999 27.738 2000 24.852 2001 23.738 2002 25.533 2003 24.094 2004 21.331 2005 26.2 2006 28.896 2007 32.637 2008 32.171 2009 25.748 2010 24.628 2011 23.541 2012 25.554 2013 27.04 2014 28.38 2015 32.499 2016 32.978 2017 30.767 2018 29.038 2019 27.218 2020 25.748 2021 24.791 2022 24.267