Year Percent 1990 53.32 1991 53.8 1992 55.127 1993 56.44 1994 57.731 1995 60.104 1996 63.067 1997 65.986 1998 65.298 1999 68.425 2000 65.61 2001 71.434 2002 72.911 2003 74.341 2004 75.725 2005 77.061 2006 78.347 2007 79.583 2008 79.163 2009 79.75 2010 80.882 2011 80.838 2012 80.61 2013 80.537 2014 79.006 2015 77.908 2016 78.419 2017 78.85 2018 79.284 2019 79.72 2020 80.159 2021 80.6 2022 81.043 2023 81.488 2024 81.931 2025 82.374 2026 82.815 2027 83.254 2028 83.694 2029 84.133 2030 84.573