Year Percent 1990 34.85 1991 35.646 1992 36.345 1993 38.756 1994 38.5 1995 38.277 1996 39.165 1997 40.231 1998 40.313 1999 42.211 2000 40.353 2001 41.361 2002 42.376 2003 42.671 2004 42.46 2005 43.519 2006 44.687 2007 44.26 2008 43.355 2009 42.861 2010 42.388 2011 42.006 2012 41.65 2013 41.302 2014 40.947 2015 40.585 2016 40.774 2017 40.919 2018 41.055 2019 41.177 2020 41.29 2021 41.427 2022 41.553 2023 41.667 2024 41.778 2025 41.894 2026 42.045 2027 42.203 2028 42.357 2029 42.494 2030 42.612