Year Percent 1990 4.558 1991 4.837 1992 5.191 1993 5.772 1994 6.925 1995 7.574 1996 8.139 1997 8.27 1998 8.334 1999 8.288 2000 7.88 2001 7.328 2002 7.01 2003 6.53 2004 5.988 2005 5.847 2006 5.541 2007 5.238 2008 5.139 2009 5.719 2010 5.543 2011 5.331 2012 5.313 2013 5.306 2014 5.348 2015 5.731 2016 5.622 2017 5.471 2018 5.32 2019 5.169 2020 5.018 2021 4.867 2022 4.715 2023 4.564 2024 4.413 2025 4.262 2026 4.111 2027 3.96 2028 3.808 2029 3.657 2030 3.506