Year Percent 1980 0.565 1981 0.588 1982 0.618 1983 0.636 1984 0.644 1985 0.651 1986 0.664 1987 0.7 1988 0.759 1989 0.821 1990 0.88 1991 0.932 1992 0.914 1993 0.975 1994 1.022 1995 1.066 1996 1.085 1997 1.014 1998 0.912 1999 0.922 2000 0.919 2001 0.928 2002 0.957 2003 0.986 2004 0.996 2005 0.99 2006 0.986 2007 0.986 2008 0.975 2009 0.972 2010 0.993 2011 0.962 2012 1 2013 0.993 2014 0.969 2015 0.967 2016 0.968 2017 0.971 2018 0.977 2019 0.979 2020 0.979 2021 0.978 2022 0.977 2023 0.977 2024 0.978