Year Percent 1990 40.34 1991 40.225 1992 40.29 1993 40.505 1994 40.829 1995 41.288 1996 41.887 1997 42.547 1998 43.296 1999 44.177 2000 45.168 2001 45.879 2002 46.618 2003 47.357 2004 48.008 2005 48.604 2006 49.473 2007 50.295 2008 51.086 2009 51.815 2010 52.496 2011 53.087 2012 53.703 2013 54.311 2014 54.836 2015 55.29 2016 55.643 2017 55.948 2018 56.253 2019 56.555 2020 56.852 2021 57.143 2022 57.43 2023 57.71 2024 57.98 2025 58.237 2026 58.483 2027 58.72 2028 58.948 2029 59.17 2030 59.387