Year Percent 1990 35.58 1991 35.943 1992 36.773 1993 37.571 1994 38.342 1995 39.114 1996 39.983 1997 40.848 1998 41.703 1999 42.535 2000 43.336 2001 44.191 2002 45.122 2003 46.077 2004 47.061 2005 48.078 2006 49.051 2007 50.08 2008 51.152 2009 52.251 2010 53.357 2011 52.87 2012 52.908 2013 52.93 2014 52.937 2015 52.931 2016 53.265 2017 53.577 2018 53.954 2019 54.354 2020 54.725 2021 54.844 2022 54.972 2023 55.133 2024 55.345 2025 55.598 2026 55.837 2027 56.107 2028 56.409 2029 56.739 2030 57.086