Year Percent 1990 24.69 1991 25.023 1992 25.219 1993 25.413 1994 25.77 1995 25.996 1996 26.2 1997 28.3 1998 24.8 1999 25.41 2000 26.031 2001 26.66 2002 27.3 2003 28.2 2004 30.643 2005 33.2 2006 29.4 2007 27.993 2008 26.627 2009 25.305 2010 22.25 2011 23.73 2012 23.81 2013 23.21 2014 23.68 2015 27.31 2016 30.88 2017 30.307 2018 29.733 2019 29.16 2020 28.587 2021 28.014 2022 27.44 2023 26.867 2024 26.294 2025 25.72 2026 25.147 2027 24.574 2028 24.001 2029 23.427 2030 22.854