Year Percent 1991 7.559 1992 7.697 1993 7.782 1994 7.799 1995 7.856 1996 8.013 1997 8.08 1998 8.642 1999 9.211 2000 9.777 2001 10.419 2002 11.095 2003 11.898 2004 12.641 2005 13.48 2006 14.471 2007 15.507 2008 16.475 2009 16.293 2010 16.162 2011 16.065 2012 16.037 2013 16.088 2014 16.098 2015 16.182 2016 16.287 2017 16.506 2018 16.734 2019 16.962 2020 17.174 2021 17.381 2022 17.583