Year Percent 1990 21.111 1991 22.142 1992 18.823 1993 19.099 1994 19.102 1995 18.533 1996 18.763 1997 18.474 1998 18.13 1999 17.648 2000 17 2001 14.5 2002 16.8 2003 13.9 2004 14.148 2005 14.4 2006 12.9 2007 13.2 2008 11.7 2009 12.3 2010 12.3 2011 10.8 2012 10.8 2013 4.8 2014 4.777 2015 4.779 2016 4.866 2017 4.674 2018 4.481 2019 4.288 2020 4.095 2021 3.902 2022 3.71 2023 3.517 2024 3.324 2025 3.131 2026 2.938 2027 2.746 2028 2.553 2029 2.36 2030 2.167