Year Percent 1990 39.494 1991 40.324 1992 41.126 1993 41.49 1994 41.442 1995 42.016 1996 42.671 1997 44.007 1998 45.355 1999 46.711 2000 48.073 2001 49.439 2002 50.799 2003 52.15 2004 53.492 2005 54.823 2006 56.165 2007 57.521 2008 58.882 2009 60.244 2010 61.606 2011 63.805 2012 65.894 2013 65.868 2014 65.811 2015 65.728 2016 65.457 2017 65.883 2018 66.307 2019 66.731 2020 67.157 2021 67.582 2022 68.006 2023 68.431 2024 68.856 2025 69.282 2026 69.71 2027 70.139 2028 70.57 2029 71.003 2030 71.436