Year Percent 1990 26.743 1991 26.953 1992 27.263 1993 27.667 1994 28.148 1995 28.7 1996 29.275 1997 29.925 1998 30.614 1999 31.294 2000 31.934 2001 32.393 2002 32.821 2003 33.212 2004 33.57 2005 33.911 2006 34.064 2007 34.671 2008 35.278 2009 35.888 2010 36.504 2011 37.123 2012 37.746 2013 38.375 2014 39.011 2015 39.655 2016 40.307 2017 40.444 2018 40.585 2019 40.726 2020 40.869 2021 41.012 2022 41.157 2023 41.299 2024 41.437 2025 41.568 2026 41.695 2027 41.816 2028 41.935 2029 42.056 2030 42.183