Year Percent 1991 13.551 1992 13.756 1993 13.777 1994 13.829 1995 11.54 1996 14.947 1997 13.936 1998 14.569 1999 15.649 2000 10.404 2001 15.411 2002 15.19 2003 14.983 2004 15.576 2005 15.262 2006 15.194 2007 15.47 2008 15.123 2009 14.789 2010 14.534 2011 15.045 2012 15.361 2013 14.955 2014 14.663 2015 14.062 2016 14.074 2017 14.073 2018 14.072 2019 14.071 2020 14.07 2021 14.069 2022 14.068