Year Percent 1991 49.027 1992 49.099 1993 42.46 1994 39.714 1995 40.909 1996 44.347 1997 44.314 1998 40.698 1999 42.428 2000 43.078 2001 45.381 2002 43.414 2003 41.957 2004 39.41 2005 38.07 2006 36.546 2007 35.523 2008 35.088 2009 34.842 2010 34.493 2011 33.344 2012 31.402 2013 29.709 2014 25.632 2015 25.678 2016 25.371 2017 25.773 2018 25.663 2019 25.65 2020 25.718 2021 25.89 2022 25.918