Year Percent 1990 38.275 1991 38.529 1992 38.71 1993 38.82 1994 38.924 1995 39.085 1996 39.355 1997 39.643 1998 39.967 1999 40.319 2000 40.678 2001 41.013 2002 40.642 2003 40.203 2004 39.691 2005 41.135 2006 41.333 2007 40.475 2008 41.241 2009 41.511 2010 42.838 2011 42.459 2012 42.946 2013 44.028 2014 45.111 2015 46.162 2016 45.192 2017 45.131 2018 45.06 2019 45 2020 44.962 2021 44.96 2022 44.976 2023 44.999 2024 45.015 2025 45.016 2026 45.026 2027 45.025 2028 45.009 2029 44.979 2030 44.934