Year Percent 1990 36.809 1991 37.438 1992 37.935 1993 38.284 1994 38.462 1995 38.469 1996 38.918 1997 39.223 1998 39.444 1999 39.65 2000 40.173 2001 40.699 2002 41.226 2003 41.756 2004 42.287 2005 42.821 2006 43.356 2007 43.892 2008 44.43 2009 45.792 2010 47.165 2011 47.956 2012 48.736 2013 49.665 2014 50.912 2015 52.567 2016 54.321 2017 54.516 2018 54.711 2019 54.905 2020 55.1 2021 55.295 2022 55.49 2023 55.684 2024 55.879 2025 56.074 2026 56.269 2027 56.463 2028 56.658 2029 56.853 2030 57.048