Year Percent 1990 90.864 1991 90.075 1992 89.074 1993 88.186 1994 86.956 1995 87.523 1996 86.727 1997 86.104 1998 85.228 1999 85.919 2000 85.313 2001 85.394 2002 85.721 2003 85.733 2004 85.621 2005 86.505 2006 86.266 2007 87.112 2008 87.576 2009 87.143 2010 86.641 2011 87.306 2012 87.566 2013 88.108 2014 87.988 2015 88.398 2016 88.48 2017 88.594 2018 88.71 2019 88.843 2020 89.003 2021 89.191 2022 89.408 2023 89.644 2024 89.882 2025 90.106 2026 90.318 2027 90.514 2028 90.696 2029 90.866 2030 91.03