Year Percent 1990 22.94688 1991 22.22222 1992 22.82609 1993 17.15736 1994 13.58961 1995 15.7665 1996 15.0986 1997 13.41793 1998 12.06176 1999 12.70056 2000 12.09683 2001 10.35043 2002 10.12843 2003 8.63563 2004 8.85025 2005 8.51859 2006 8.57873 2007 8.30317 2008 8.66625 2009 8.13139 2010 8.89152 2011 8.00176 2012 8.13105 2013 6.80912 2014 7.30339 2015 6.28295 2016 6.89528 2017 7.5661 2018 6.59009 2019 6.79497 2020 7.07716 2021 6.70684 2022 7.70847