Year Percent 1990 77.05 1991 77.087 1992 77.177 1993 77.319 1994 77.291 1995 77.195 1996 77.071 1997 77.417 1998 77.66 1999 77.924 2000 76.621 2001 81.581 2002 80.002 2003 78.092 2004 75.715 2005 76.913 2006 78.065 2007 79.157 2008 80.197 2009 81.02 2010 81.844 2011 81.608 2012 81.374 2013 81.152 2014 80.972 2015 80.823 2016 80.7 2017 80.94 2018 81.19 2019 81.418 2020 81.603 2021 81.751 2022 81.859 2023 81.939 2024 82.014 2025 82.099 2026 82.195 2027 82.302 2028 82.416 2029 82.53 2030 82.641