Year Percent 1990 46.5 1991 46.46 1992 46.42 1993 46.38 1994 46.34 1995 46.3 1996 46.24 1997 46.18 1998 46.12 1999 46.06 2000 46 2001 46.3 2002 46.599 2003 46.899 2004 47.2 2005 47.5 2006 47.393 2007 47.432 2008 47.212 2009 47.195 2010 46.193 2011 46.455 2012 46.388 2013 46.442 2014 46.381 2015 46.214 2016 46.156 2017 46.142 2018 46.128 2019 46.114 2020 46.1 2021 46.086 2022 46.072 2023 46.058 2024 46.044 2025 46.03 2026 46.016 2027 46.002 2028 45.988 2029 45.974 2030 45.96